If you do not currently have your IGN linked to your forum account, it is quite a simple process. To link your account, simple copy the command either at the top of every page or on the account creation page, and run that in game. You should then get a message in game informing you whether or not it was successful. If it failed for whatever reason, please contact a staff member, or post in the help section.
Linking your forum account helps us and others determine what account the forum account belongs to. It also sets your profile picture to your player head.