Dr. Andy Williams has produced a complete CSS course. It takes an absolute beginner from the basics of CSS to advanced layouts, in just a few lessons.
If you are unfamiliar with CSS (Cascading Style Sheets), they are the new standard way to format and design web pages. With HTML, you had to modify each design element of each page individually. If you wanted to change the look of your site, it could take hours, or even days. With CSS, it only takes a few seconds.
With CSS, your pages will load faster, look better, be easier to modify, faster to change layouts, and be free of those pesky HTML tables. Best of all, you can get this get this handy CSS reference guide, for less than the cost of a pizza.