You can learn just about anything about Web development online for free.
For learning basic HTML, CSS and JavaScript, start at Codecademy. For me it was time well spent.
Other helpful general knowledge sites include:
- Mozilla Developer Network (MDN)
- Google Developers Web Fundamentals
- Shay Howe’s HTML and CSS
- Google HTML/CSS/Javascript from the Ground Up Class (Videos)
- Tuts+
- HTML Goodies
- Move The Web Forward
- Web Platform
- Sitepoint
- Quackit
- Webmonkey
- W3schools
Further Reading: