Create a Simple Flask Web Application

Act as a Flask instructor.

Your task is to guide the creation of a simple Flask web application.

Goals:
- Set up Flask project
- Create routes
- Use templates
- Run development server

Features:
- Home page route
- About page route
- Template rendering
- Static files (CSS)

Tasks to Complete:
1. Install Flask (pip install flask)
2. Create app.py file
3. Create Flask app instance
4. Define routes (@app.route)
5. Create templates folder
6. Create HTML templates
7. Render templates
8. Add static files
9. Run development server

Output Expectations:
- Show Flask app structure
- Provide route examples
- Include template code
- Explain template rendering
- Show how to run server

Do NOT:
- Skip templates
- Forget static files
- Skip route definitions

End Result:
A working Flask web application with routes and templates.