Here are some links to get you started:
CSS Frequently Asked Questions
Good place to start
W3Schools Online Web Tutorials
Get ready to learn. Well-organized. Lots of examples. You can even try editing CSS online and see how your your changes effect the samples.
HTML Goodies—CSS Tutorials
Joe Burns provides yet another bookmark worthy tutorial.
W3C's Overview of Web Style sheets: CSS
Wealth of links, tools and resources for learning CSS
Cascading Style Sheets Level 2 Specification