As you may have noticed our forum has the Rep system installed, and here are the basics of it.
Most of the time it will be related to Classifieds, if you have had a successfull sale from somebody give him positive rep, if you had a horrible experience, neg rep it is.
Rep system abuse will be closely moderated.
Rep may also be awarded for great posts, weither informative or really funny, and on the flip side abusive posts will be awarded neg rep.
Have fun!