The ratings thing is kind of confusing when you first see it but the idea is simple. At the bottom of each message thread (not each individual message but the whole thread) there is a place where you can rate each message from 1 to 10. It will be in red. Anyone who is logged in can rate the thread and the ratings are averaged to yeild the total rating number that you see by the thread. Basically it's a chance to say, hey this thread is worth reading, or hey this thread is a waste of bandwith!
I think all of this stuff is described if you click "help" not that most people including me, would want to read that, but it's in there.