Great. Here's a good place to begin:
In a nutshell, this is the way it works. 12 tiers (including the swapmeister) tie up flies for the swap. Tie 11 flies if you don't want one of yours back. Tie 12 if you do. Once your flies are tied (before the due date), you let the swapmeister know, and he/she sends you a PM with a mailing address. You toe tag your flies, box them up (Altoid tin works great) and mail them off to the swapmeister, along with a self-addressed and postage paid envelope. Once all the flies are in, the swapmeister divides them up so everybody gets one of each, and he/she mails them back out. Easy peasy.
Swapmeisters also have some rules:
Wanna give it a go?