Gwen, if you look below every post/comment/reply, there are icons there beside the words "Add as Article". You can see a star there and that's how you can give "I approve" rep (positive rep) and "I disapprove" rep (negative rep). I think you can only give reps once you become a Respected Member. But don't worry, the more helpful posts and reps you get, you can get promoted automatically. The green blobs below your name are your reps, green for positive and red for negative. If you get a negative rep, your green blobs would be lesser till you can only see red blobs if you got a lot of negative rep (hopefully not!). You can check all the reps you got by clicking "Settings" at the right top corner of the forum page. You would not know who gave you a rep unless they put their name.