Lesson 1: what Claude Code is and how to install it in 15 minutes

After this lesson, you will be able to do three things: understand what Claude Code is and why business people (not just programmers) are rushing to use it, install it on your own machine, and read its first screen without feeling overwhelmed. That's all, but this is the foundation lesson of the whole course, and we advise you not to skip ahead.

What Claude Code is, in plain English

Claude Code is an AI assistant that runs right on your computer, instead of on a website like the ChatGPT or Claude.ai you're used to. It sounds like a small difference, but it changes the whole nature of the thing.

A web AI chat is like an adviser on the phone: it answers whatever you ask, but it can't touch your actual work. Claude Code is more like an assistant you've sat down at your own desk: it can see your folders, open files, edit documents, write programs and tidy up the messy pile of files on your machine. You give orders in plain language, and it does the whole chain of work itself, start to finish.

So don't let the word “Code” in the name put you off. Programmers do use it a lot, but what's valuable for a business owner lies elsewhere: it can do office work and operations work directly on your own real data. It's also the tool MONA engineers use every day to deliver projects faster, so we teach this course from real hands-on use, not from reading documentation and retelling it.

One thing to know up front: AI tools change their interface constantly, and within a few months a button can sit somewhere else. So what you need to remember isn't “which colored button is in which corner” but the official place to look things up: the official documentation at code.claude.com/docs. Stuck somewhere? Open it.

Preparation: your account and plan

Claude Code is not included in the free plan. You need at least the Pro plan from Claude (sign up at claude.com; the list price depends on when you read this, around a few hundred thousand dong a month). For beginners, Pro is enough to use all day. We'll be honest: compared with having an extra assistant who can do all kinds of work on your machine, this fee is one of the best-value software fees a business person pays each month.

Once your account is registered, the paid part is over. Everything from here on is free.

Installation: just one line of command

The cleanest way to install Claude Code is through the terminal. Many of you may shudder at the word terminal, but relax: the terminal is just a window for typing commands to your computer, and you only need one command.

Open the terminal:

• Mac: press Command + Space, then type Terminal, Enter.
• Windows: press the Windows key, then type PowerShell, Enter.

Then paste the install command (the latest one is always in the code.claude.com/docs installation section):

• Mac / Linux: curl -fsSL https://claude.ai/install.sh | bash
• Windows PowerShell: irm https://claude.ai/install.ps1 | iex

Your machine will print a stream of text that looks very “dark and arcane”. Ignore it, that's perfectly normal. When it finishes, check with the command claude --version. If the machine returns a version number, the install worked.

From now on, to call the assistant, type just one word: claude. The first time you open it, it will ask you to log in. Choose to sign in with the Claude account with the Pro/Max plan you just registered (don't choose pay-per-use API billing, which is both more complicated and more likely to cost you extra as a beginner). The browser pops up, you click confirm, go back to the terminal, and you're done. If you accidentally closed the login screen, type /login inside Claude Code to log in again.

Reading the first screen without getting overwhelmed

Open claude up, you'll see a screen packed with text. Only a few things on it deserve your attention:

• The model in use: the line showing the model name (for example Opus, Sonnet). The model is the “brain” answering you; the higher your plan, the better the brain you get.
• The working folder: Claude Code always “sits” in a specific folder on your machine. It states the path at the very start of the session. This is the key difference from web chat: it is INSIDE your computer, in exactly that folder.
• The command box: where you type your requests, just like a chat box.
• The permission mode: at the bottom corner, press Shift + Tab to cycle through them. By default it asks permission before touching files. There is a “plan first” mode (plan mode) and a skip-permissions mode that the community talks about a lot. In lesson 4 we'll go through which mode to use when to stay safe; for now, just leave the default.
• Tokens and context: the machine counts “words” in units called tokens (a word is a little more than one token). And context is the percentage of conversation memory used. These two numbers become a big deal in lesson 6, because how well you manage context decides whether the machine works smart or dumb. For now, just know they're there.

Try your first sentence to get the feel: type “hi, which folder are you in, and what's inside it?” and press Enter. It will look at the folder and tell you. That feeling of “it can see my machine” is exactly what web chat never gives you.

Terminal or graphical interface: which one?

Besides the terminal, Claude Code also works inside an IDE. An IDE sounds fancy, but it's really three things combined: a folder manager, a file editor and an AI chat panel, all in one window. Two popular IDEs today are Visual Studio Code (long-established, made by Microsoft) and Antigravity (newer, built on top of VS Code and strongly focused on AI).

With VS Code: download it from the Visual Studio Code home page, open it, go to the extensions section (the icon of squares on the left edge), type “Claude Code” and install the version from Anthropic with the verified checkmark. This matters: only install extensions from the official developer, since shady ones have been caught installing malware. Once installed, you get a Claude Code chat panel right inside VS Code, so you don't have to stare at the terminal.

Our honest advice: the graphical interface is easy to get used to, but you should practice with the terminal version. The terminal can run multiple sessions in parallel, runs faster, and later every great technique (lessons 9 and 10) works at its best in the terminal. From lesson 2 on, we work mainly in the terminal, and we'll point out where an IDE is more convenient.

Try it yourself before moving on to lesson 2

1. Sign up for the Pro plan, install Claude Code, run claude --version and see the version number.
2. Open claude, log in, and ask it your first question about the folder it's standing in.
3. Press Shift + Tab a few times, watch the permission mode names cycle, then return to the default.
4. Open code.claude.com/docs and save it as your reference.

In lesson 2, we let you do something most beginners don't believe they can do: build a working web app just by describing it in words, and learn the most important concept of the whole course: the CLAUDE.md file, the “project brain” that helps the machine understand your work like a trained employee.