If you can't make heads or tails of CSS, floating divs, absolute positioning then you should take a look at these books:
Eric Meyer is an internationally recognized expert on the subjects of HTML, CSS and web standards. He uses a light witty writing style to make a bland and boring subject palatable and interesting. In his "Eric Meyer On CSS" books he walks the reader through practical examples to get the reader up to speed with a set of CSS concepts. Each lesson is a different web site with different requirements in layout and navigation. The reader comes away with techniques that can be applied directly to his/her own project or can be adapted to his/her own needs.
An excellent reference and a must have for any web developer "Cascading Style Sheets: The Definitive Guide" provides the theory, strengths and uses of CSS. Eric Meyer starts from the beginning of what the web was like before CSS and what CSS brings to the table in terms of formatting, layout, and a developer's time. This book is DOES NOT get in to practical examples like the "Eric Meyer On CSS" books. Eric breaks down each tag and element to give you a thorough knowledge of CSS. If you are looking for a cookbook style book on CSS this is NOT it.