There's a couple of different games over there. One is, people post best answer questions for each other. These usually begin with a screen name or a person's given name, and involve only the two people playing. If you want to do this, post or answer a question that says "anyone want to trade?"
Questions that say best answer are open for everyone and are usually rewarded either at random or to the first answerer.
Bump posts are asking you to bump them, usually so they can get an award. If you answer as well as bump, most posters will vote up your response, as well as most people who answer the post as well.
People also post questions to give away voteups, and many of these you can answer as many times as you want.
Just read each poster's rules and have fun earning credits!
at 5:31 AM on Oct. 9, 2010