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A free guide by Mariah Brunner ↗ INSTAGRAM ↗ TIKTOK

What’s An
.md File?
(Crash Course)

Markdown files sound technical. They’re not. They’re plain text AI reads easily, and they’re how AI agents know how to work with you. Here’s the simple version, plus a template to build your first one.

AI sounds complicated, but I’m going to break down one of the most important pieces so you can actually learn it and not get left behind.

An md file (a markdown file) is just a plain text file with simple formatting so AI can read it easily. When you work with AI, it reads files like this to know how to work with you. Here’s the whole "language" you’ll actually use.

01

Headings

# Title makes a big heading. More hashes (##, ###) make smaller sub-headings.

02

Bullets and numbered steps

- item makes a bullet point. 1. step makes a numbered list for steps in order.

03

Bold

**bold** makes text bold. That’s basically it. Plain words plus those few marks. (Full cheat sheet if you’re curious.)

Files Are How Agents Think

An AI agent isn’t super complex either. It’s a smart assistant that knows how to read the right file at the right time.

An agent setup is usually a folder of md files that spell out your preferences, your business or job, and your repeatable workflows. The agent reads them like a table of contents and opens the right one when it needs it. You can see this everywhere already. Claude Code reads a file called CLAUDE.md, every Claude Skill is a SKILL.md file, and many coding agents read AGENTS.md.

In Plain English

A markdown file is a note you write for your AI instead of a person. An agent is an assistant with a folder of those notes and the sense to grab the right one. Once that clicks, building your own stops being scary.

Build Your First File

The most useful file to start with is a "How I Work" file. It’s a one-page note that tells any AI who you are, how you want it to talk to you and what you need help with, so you stop re-explaining yourself in every chat.

Pick one of three ways. Fill in the template, let AI interview you with the prompt under it, or open Claude, turn on voice-to-text, ramble, and say "turn this into a clean markdown file."

Your "How I Work" File (Fill In The Brackets)
# How I Work Last updated: [Month Year] Privacy note to myself: keep this to context, not secrets. Do NOT put passwords, card or bank numbers, IDs, customer personal info, or my home address in here. ## Who I Am - What to call me: [your name or nickname] - What I do: [your job or business in one line, e.g. "I own a 6-person dog grooming shop in Austin and run all the marketing myself"] - My experience with AI: [brand new / some / pretty confident] ## My Goals - This year: [the big one, e.g. "grow from 40 to 70 appointments a week"] - Right now / this quarter: [your current focus, e.g. "launch a monthly membership"] - Success looks like: [how you will know it worked, e.g. "15 members signed up by Sept 1"] ## How I Want You To Talk To Me - Tone: [casual and direct / warm and friendly / strictly professional] - Reading level: [keep it plain and simple / fine to get technical] - Length: [short and to the point / give me the detail] - Emojis: [none / a few are fine] - Format: [use bullets and tables when they help; keep explanations to one tight paragraph] ## Give Me A Recommendation, Not A Menu - When there is a choice to make, tell me what YOU would do and why, then the runner-up. Do not just hand me a long list of options and make me decide alone. ## Challenge Me, Do Not Just Agree - Push back if my idea is weak or my facts are off. Point out risks I am missing. I would rather be corrected now than embarrassed later. ## When You Are Not Sure, Ask - If you do not know, or my request is unclear, say so and ask me one question. Never guess, and never make up facts, numbers, or quotes. ## About My Work - Who I serve: [your customer or audience, e.g. "busy pet owners, mostly women 30 to 55"] - What I sell or do: [your products or services, with prices if it helps, e.g. "full groom, $85"] - Key facts and numbers: [anything that makes answers useful, e.g. "slow days are Mon and Tue; my main competitor charges $110"] ## Tools I Use - [the apps and systems you actually use, e.g. "Square for booking, Canva for graphics, Instagram and Gmail for marketing"] ## What I Ask For Most 1. [your most common task, e.g. "Instagram captions"] 2. [e.g. "replies to unhappy customers"] 3. [e.g. "turning my rough notes into clean, professional emails"] ## My Words (so you do not misread me) - [your shorthand and industry terms, e.g. "'a full' = a full-groom appointment, 'the book' = my Square calendar, 'regulars' = clients who come every 4 to 6 weeks"] ## Never Do This - [your hard rules and pet peeves, e.g. "never invent statistics, never use buzzwords like 'unlock' or 'next level', never write more than I asked for, do not lecture me on basics I already know"] ## What Great Looks Like (paste real examples) - Here is something I wrote that I liked. Match this style and energy: [paste 1 to 3 real samples of your own writing, like a caption or email you were proud of. Real examples teach your voice far better than any description.] ## Good To Know (optional) - My time zone: [e.g. US Central] - When I work best: [e.g. early mornings and after 8pm; low energy midday] - Anything else that helps you work with me: [...] --- For the AI: Read this file first in every conversation and use it to work the way I work. If anything here looks out of date, point it out and ask me.

Prefer not to fill in blanks? Paste this into Claude or ChatGPT and it’ll interview you and write the whole file in about 10 minutes.

Let AI Build It For You
You are my AI setup coach. Your goal is to build my "How I Work" file: a one-page markdown file that tells any AI who I am, how I work and how I want help, so I never have to repeat myself again. HOW TO RUN THIS 1. Interview me. Ask ONE question at a time, wait for my answer, then ask the next. 2. Cover, in this order: who I am and what I do, my goals (this year and right now), how I want you to talk to me (tone, length, emojis, format), how I like decisions made, who I serve and what I sell, the tools I use, the 3 tasks I ask AI for most, my shorthand and industry words, my pet peeves and hard rules, and 1 to 3 real samples of my writing that I love. 3. Ask 12 to 15 questions total. Keep each one short and plain, and give a quick example answer so I know what you mean. 4. If an answer is vague, ask one follow-up before moving on. WHEN WE'RE DONE - Write the whole thing as ONE clean markdown file with these headings: # How I Work, ## Who I Am, ## My Goals, ## How I Want You To Talk To Me, ## About My Work, ## Tools I Use, ## What I Ask For Most, ## My Words, ## Never Do This, ## What Great Looks Like. - Put "Last updated: [this month and year]" under the title. - End with a short note: "For the AI: read this first and work the way I work. If anything looks out of date, ask me." - Then tell me in 2 lines where to save it in the AI I'm using. RULES - Only write what I told you. Don't invent goals, numbers or facts about me. - If I share a password, card number, ID, home address or a customer's personal info, leave it out and remind me it doesn't belong in this file.

One Rule Before You Paste

Keep this file to context, not secrets. Your role, goals, voice and business facts are fine. Passwords, card or bank numbers, IDs, customer personal info and your home address stay out. If you wouldn’t post it on a public website, leave it out.

Now Plug It In

A file sitting in a note does nothing. Start with the easy way, then set up your tool so you never paste it again.

04

The easy way, paste it on top

Start a new chat and paste your whole file first, with this line above it: "This is my How I Work file. Use it for everything in this chat. Confirm you have it, then wait for my question." It works in Claude, ChatGPT, Gemini, any of them.

05

In Claude, set it once

For every chat. Click your initials in the lower left, then Settings, then Your Claude, and paste it under Instructions. (On the older layout it’s Instructions for Claude.) (Anthropic’s guide)

Even better, make a Project. Click Projects, then New Project, name it "About Me," click Set project instructions and paste your file. Then add the .md file to the Project’s files. Every chat in that Project knows you. Free accounts get up to five Projects.

06

In ChatGPT, use custom instructions

Go to Settings, then Personalization, then Custom instructions. Paste your how-to-talk-to-me and never-do rules into the custom instructions box. If your screen also shows a separate about-you field, put the who-you-are part there. Free plans have a tighter character limit, so paste a short version there and keep the full file for a ChatGPT Project.

Keep It Alive

Every time you catch yourself re-explaining something, add that line to the file and update the date. Once a month, refresh your goals. To test it, ask: "Based on my file, how should you talk to me and what should you never do?" If it repeats your rules back, you’re wired in.

The Real Win

Once markdown clicks, you understand how agents are built, and a whole new world of AI opens up. Your "How I Work" file is step one.