Hrm, it has been a long time since we transferred. It used to be that you would receive an in game mail that would give directions. If that's not there, go to:
--> Blizzard Battle.net
--> Blizzard Dropdown on top left
--> Account Management
--> Click your Warcraft game subscription from the list of Game Accounts
--> Character and Guild Services (near the bottom)
--> Character Transfer
Unfortunately, there is a $25USD cost (this is not a decision we made lightly!).
We are on Aggramar/Fizzcrank. They are joined servers, so transferring to either is fine. But, if you want to be super particular, the guild itself is established on Aggramar. Going to Fizzcrank is handy if your name is locked on Aggramar!
Look forward to seeing you online! Things have been in a bit of a lull while we wait for the next raid, but I expect to pick up a bit over the next month.