A close friend has asked that I perform his marriage ceremony...we are both open-minded religious folk...I have completed the online ordination process...what should I do to ensure that I can legally conduct the service that my friend has requested? I am in Georgia.

You should contact the county clerk in the county where the marriage is to take place and register with them. They will let you know what documentation, if any, that you need to provide. Once you are registered with them, the ceremony is all you have left to do.