HTML Dog has probably been the most useful tool in this whole ordeal for me. Here, in the intermediate tutorial, Patrick Griffiths explains the difference from the ID and the div tags. ID tag's identify a particular rule, whereas divs describe classes. Though not vital information, this can probably help alleviate some frustration, and for that, it's worth checkint out.
Designer Jean Louis gives a pretty cool tip about sizing text without pixels. It's one of those tricks that makes text fit according to your site. Using percentages next to the body div on css will enable you to do this. I'm going to try it when I design my next site while playing around with text.