I learned CSS last semester. It was rushed, covering simple HTML (which I already knew) and moving into CSS at a blinding speed. It took me quite a while to figure out how CSS works.
Today I saw this article, which would have made the learning process much faster and less painful. The writer assumes some basic knowledge of CSS, but outlines very well the process of creating a layout and using divs. He does use one IE hack, but the article assumes the use of IE 5, which had more problems with CSS and is not very widely used anymore.
He also uses a very cool technique for navigation.