Getting Started with Claude Code: Ship Your First Feature in 30 Minutes

What Claude Code Is (and Is Not)

Claude Code is Anthropic's command-line coding assistant. It is not an IDE plugin or a code completion tool. It is an agent that lives in your terminal, understands your entire codebase, and can read files, write code, run commands, and execute multi-step development tasks.

Think of it as pairing with a senior developer who has read every file in your project and can make changes across multiple files simultaneously. You describe what you want in plain English, and Claude Code implements it.

We use Claude Code daily at Fusion Interactive for client projects. It has fundamentally changed how fast we ship. This guide will walk you through installation, configuration, and building a real feature from scratch.

Installation (5 Minutes)

Claude Code requires Node.js 18 or later. If you do not have Node.js installed, download it from nodejs.org.

Install Claude Code globally:

npm install -g @anthropic-ai/claude-code

Navigate to your project directory and start Claude Code:

cd your-project
claude

On first launch, Claude Code will ask you to authenticate with your Anthropic account. Follow the browser prompt to log in. You need an active Anthropic plan (either the Max plan or API credits).

Once authenticated, you will see a terminal prompt where you can type natural language instructions. Claude Code will read your project files and build an understanding of your codebase.

Understanding How It Works

Claude Code operates with a few key concepts:

• Context window: Claude Code reads the files relevant to your task into its context. It understands file relationships, imports, type definitions, and project structure. You do not need to tell it which files to look at. It figures that out.
• Tool use: Claude Code can read files, write files, run shell commands, and search your codebase. When you ask it to do something, it plans the approach and uses these tools to execute.
• Permissions: By default, Claude Code asks for confirmation before writing files or running commands. You can adjust this based on your comfort level.
• Memory: You can create a CLAUDE.md file in your project root with instructions, conventions, and context. Claude Code reads this at the start of every session.

Your First Feature: Adding a Contact Form

Let us walk through building a real feature. Suppose you have a Next.js application and want to add a contact form with server-side validation and email delivery.

Step 1: Describe what you want

In the Claude Code terminal, type:

Add a contact form to the /contact page. It should have fields for name, email, company (optional), and message. Validate on the server side. Send the submission via Resend to info@mycompany.com. Show a success message after submission. Style it with Tailwind to match the existing site design.

Claude Code will analyze your project, identify the relevant files, and present a plan. It might look something like this:

• Read the existing /contact page to understand the current layout
• Check package.json for existing form libraries and email services
• Create a server action for form handling and validation
• Create the form component with client-side interaction
• Integrate Resend for email delivery
• Add the form to the contact page

Step 2: Review and approve

Claude Code will start implementing. As it writes files and runs commands, it will ask for your approval. Review each change before accepting. You can:

• Accept the change and continue
• Ask Claude Code to modify the approach
• Reject the change and provide different instructions

Step 3: Iterate

After the initial implementation, test the form. If something is not right, describe the issue:

The form validation shows errors but they disappear too quickly. Keep the error messages visible until the user fixes the field. Also, add a loading spinner on the submit button while the form is sending.

Claude Code will read the current implementation, understand the issue, and make the targeted changes.

Effective Prompting Patterns

After months of daily use, we have identified the prompting patterns that get the best results:

Be specific about behavior, not implementation

Good: "When a user submits the form with invalid data, show inline error messages below each field and focus the first invalid field."

Less effective: "Use react-hook-form with zod validation and display errors."

Describe the behavior you want and let Claude Code choose the implementation. It often selects a better approach than you would have specified.

Reference existing patterns

Build the new settings page following the same layout pattern as the existing /dashboard/profile page. Use the same form components and validation approach.

Claude Code will read the referenced page and replicate the patterns. This maintains consistency across your codebase.

Provide context for business logic

Add a discount calculation to the cart. Our pricing rules: orders over $500 get 10% off, orders over $1000 get 15% off. The discount applies to the subtotal before tax. Display the discount as a separate line item in the order summary.

Claude Code handles the technical implementation. You provide the business rules. This is the ideal division of labor.

The CLAUDE.md File: Your Project Brain

Create a CLAUDE.md file in your project root. This is the single most impactful thing you can do to improve Claude Code's effectiveness. Include:

• Tech stack: Frameworks, libraries, and versions your project uses.
• Conventions: Naming patterns, file structure, coding standards your team follows.
• Business context: What the application does, who the users are, and important domain terminology.
• Common commands: How to run the dev server, run tests, build for production.
• Do's and don'ts: Specific patterns to follow or avoid. For example: "Always use server actions for form submissions, never API routes."

Claude Code reads this file at the start of every session. The better your CLAUDE.md, the fewer corrections you will need to make during development.

Real Productivity Gains

We track our development velocity at Fusion Interactive. Here is what Claude Code has done for our team:

• Feature development: 2-3x faster for standard features (forms, CRUD interfaces, API integrations). The time savings come from less boilerplate writing and fewer context switches.
• Bug fixing: Significantly faster for bugs that span multiple files. Describe the bug, and Claude Code traces the issue across your codebase.
• Refactoring: Renaming, restructuring, and migrating code across dozens of files in minutes instead of hours.
• Learning new libraries: Claude Code knows how to use most popular libraries. Instead of reading documentation, describe what you want to accomplish and it implements with the library's best practices.
• Testing: Generate comprehensive test suites by pointing Claude Code at your implementation and asking it to write tests. It identifies edge cases you might miss.

Where it does NOT help: architectural decisions, novel algorithm design, and creative problem-solving. Claude Code excels at implementation, not invention. Use it to build what you have already decided to build.

Common Mistakes to Avoid

• Not reviewing changes: Claude Code is capable but not infallible. Review every change it makes, especially for security-sensitive code. Auto-accepting everything is tempting but risky.
• Prompts that are too vague: "Make the app better" will get you something, but probably not what you wanted. Be specific about what better means.
• Ignoring the CLAUDE.md file: This is the highest-leverage thing you can do. Ten minutes of writing project instructions saves hours of corrections.
• Using it for everything: Sometimes opening a file and changing one line is faster than describing the change in English. Use the right tool for the job.
• Not learning from its code: Claude Code often implements patterns you might not have considered. Read its code. Learn from it. Your own skills improve alongside your productivity.

Getting the Most Out of It

Claude Code is a multiplier, not a replacement. The developers on our team who get the most value from it are the ones who understand their codebase deeply and can quickly evaluate whether Claude Code's output is correct.

Start with a small feature. Get comfortable with the workflow. Learn what makes a good prompt versus a bad one. Then gradually expand to more complex tasks.

The developers who resist AI tools will fall behind. The developers who blindly accept AI output will ship bugs. The developers who thoughtfully collaborate with AI tools will build better software, faster, than either approach alone.

At Fusion Interactive, Claude Code is part of how we deliver projects faster and at higher quality for our Toronto clients. If you want to see what AI-assisted development looks like in practice, check out the case studies on our site or reach out for a conversation about your next project.