You can convert points into credits or cash. To do this, simply click on the "Convert Points" link in your account menu.
You buy things in the point store.
You use the points to play games once you convert them to game points.
You can bid on the Super Money Auction at PaidHitWorld.com every month I give away to the top bidder $5.00. There will always be a link in the featured links to right of the page.