Module 1 · Learn to drive: how to tell AI what to build

Build your first tool in 15 minutes

Enough theory — you’re going to build a real, working tool right now. A one-page price-quote calculator for your own services, done in a single prompt and one small tweak. Fifteen minutes from now you’ll have software you made yourself.

What you’re building

A simple web page you open on your computer: your services listed with checkboxes and quantities, and a big running total that updates as you click — so you can quote a price on the spot while a customer’s on the phone. It’s a Pattern B tool: once built, it runs entirely on its own, forever, for free.

Step 1 — paste the kickoff prompt

Open Claude Code in your my-tools folder (start a new sub-folder for it if you like, e.g.my-tools/quote-calculator). Copy the prompt below, swap in your real services and prices where the bracket is, and paste it in.

I want to build my first tool: a simple price-quote calculator for my business.

The job: help me quickly quote a price while I'm on the phone with a customer.

The input: I'll give you my list of services and prices right now: [YOUR SERVICES AND PRICES — for example: "Deep clean — $220. Standard clean — $140. Move-out clean — $310. Add-on: inside fridge — $35."]

The output: a single web page I can open on my computer. It shows my services with checkboxes and quantity fields, and a big running total that updates as I click. A "copy quote" button that copies a tidy summary I can paste into a text or email.

The look: clean and simple, easy to read, works on my phone too.

The boundaries: everything runs in the page itself — no internet, no accounts, no data stored anywhere.

Before you write any code, tell me your plan in plain English. Keep it simple — this runs on my computer, just for me.

Claude will answer with its plan first — a short, plain-English description of what it’s about to make. Read it. If it matches what you pictured, tell it to go ahead (“looks good, build it”). If something’s off, say so in plain words before it builds. Then it writes the tool.

Step 2 — open your tool

When it’s finished, ask Claude how to open it — “how do I open this?” It’ll tell you exactly what to do, which is usually one of two things: double-click the file it made (its name ends in .html), or open a local web address it gives you. Either way, your calculator opens in your normal web browser. Click a few services, watch the total move.

Step 3 — make your first change

Real tools grow one request at a time. Practice that now with a single, useful tweak. Type this into the same conversation:

Add a checkbox for "returning client" that takes 10% off the total when it's ticked.

Claude updates the page. Refresh it in your browser and try the new checkbox. That loop — look at it, ask for one change, look again — is how every tool in this course gets better. The next lesson is all about doing it well.

Watch this step

Here's the same kind of first build on screen: a beginner going from empty folder to a working app in one sitting, no code typed by hand — mirroring the warm-up below. It’s from an independent creator — credited below, so go give them a follow.