Credits can be used as payment. For like requests, signature's (.psds), but it also for the Go there and you can buy stuff you like. Every post you make, you gain 1 Credits, exept in folders like Off-Topic and introducions.
At the left of a post you see: Group: Member Posts: 66 Member No.: 97,765 Joined: 13-July 06 Reputation: ... pts Wealth Statistics GR Credits: 0 Donate Credits You need to look at the Credits, there you see how much you have. But you can also click the button in the header, it takes you to the shop and you see at the left: Your GR Credits: ... Its at top in the menu.