w3schools is a GREAT place to start. It teaches you the basics and then you can go on from there. After you've gone through their tuts then go out and find more complicated tuts to teach you more about it, and how to code full-on layouts. What I did, is go through w3schools, then I found another basic tutorial for a review on the CSS etc, and then I studied some code from websites. I picked up XHTML/CSS to the useable ability within 2 days or so. Then as you keep coding etc, you advance and get better.

Another great way to learn is to order the "For Dummies" books. They explain everything thoroughly and it would also help to have the book for quick reference when you forget what things do etc.

Hope this helps!
Cushioned