On this forum you will notice on post on the right some green blobs (or red if your very naughty). This is your Reputation level.

How do you get it? Also on the post on the right you will see a Scales Icon. If you like someones post (or dislike), or want to thank them, you can click the scales, and add Rep to them (or take it away). Yo also can leave a comment.

You can view your own Rep comments by clicking USERCP in the top left.

You can not see who posted the Rep, but if people want to sign the comment that is fine. By clicking on the comment in the USERCP it will tale you to the thread you got Rep for.