Why don't you start with the two tutorials available through the stick at the top of the css forum.

There is one that gives you layout templates as a starting point for a web site with information on what goes where and why.

Then there is one that will show you how to build css driven menu systems.

For a good grounding in all the different (x)html tags (elements) and how to use them, try this site:
http://www.w3schools.com/tags/