Yo~!

The gold coins are just a result of being active here on the forums. They correspond with a certain amount of experience and is fit into *gorithm to determine how much experience you have:
( Total credits=Posts+Digest postsX5+PopularityX2+EXP+Contribution )

THe amount of experience you have will change your "rank" in the forums. Ninja Student, Beginner Genin, Genin, etc... With each rank you progress to, the more privileges and perks you get to use in the forums.

Hope this helped!

Cheers :victory: