The code I've been looking at on other people's sites has been somewhat confusing, but I figure I'm just familiarizing myself with things and will understand more when (1) we study it in class or (2) I have a reference book in which to look things up. I've looked at Shannon's O'Reilly HTML book, but it has only 3 pages on the <div> tag and nothing about how it interacts with CSS. Still, I should read it more carefully, and I've found that there is plenty of information online.
Now my brain is tired. I think I'll go watch some tv, and see if my brain recovers so I can do some more research before dinner.