Lesson 3Basics

Your First Session

Hands-on introduction

Starting a Session

Open terminal at your project root and run Claude:

$ cd my-project
$ claude
✓ Project detected: my-project
✓ Git repository found
✓ Found CLAUDE.md with instructions
> _
Basic Commands
/helpShow help for commands
/clearClear chat history
/compactCompress context while keeping essence
/modelSwitch model (sonnet, opus, haiku)
/costShow token usage
Ctrl+CInterrupt current operation
EscapeCancel current input
Natural Language Interaction

Just describe what you need, as if talking to a colleague:

> Show me the project structure
Analyzing directory structure...
📁 src/
├── components/
├── pages/
└── utils/
> Which tests are failing?
Running tests... Found 2 failing tests in auth.test.ts
Editing Files

Claude shows diff before applying changes:

> Add email validation to the registration form
Editing src/components/RegisterForm.tsx
- const handleSubmit = () => {
+ const handleSubmit = () => {
+ if (!validateEmail(email)) {
+ setError('Invalid email');
+ return;
+ }
? Apply changes? [y/n]
Running Commands

Claude can run any commands (with your permission):

> Run tests and fix the errors
? Execute: npm test? [y/n]
y
✓ Tests running
❌ 1 test failed: UserService.test.ts
Analyzing error...
Creating Commits

After making changes, ask Claude to create a commit:

> Commit these changes
Analyzing changes...

Proposed commit:
feat(auth): add email validation to registration form
- Add validateEmail helper function
- Implement validation in RegisterForm
- Add error message display
? Create commit? [y/n]

Example Tasks

Fixing a bug
> In auth.ts the login function doesn't handle empty password case. Fix this.

→Claude reads file, finds function, adds validation, shows diff

Writing a test
> Write a unit test for the calculateTotal function in utils.ts

→Claude analyzes function, creates test file, runs verification

Refactoring
> Split UserProfile component into smaller components

→Claude analyzes structure, proposes plan, creates new files

Tips for Your First Session

  • •Start with simple tasks to understand how Claude works
  • •Be specific in requests — mention files and functions
  • •Use /compact if context becomes too large
  • •Don't hesitate to interrupt (Ctrl+C) if Claude goes off track