The cup will always chase the disc. Only one of the sides of the cup will mark the disc and call out the stall count. (Nobody else may do this.) The other people in the cup play exactly ten feet off the disc unless there is an offensive player within ten feet in which case the defender may follow him/her in. When the disc is swung, the cup tries to contain passes from getting up the field before tightening up again. The middles look to cover offensive players in their zone paying special attention to the passing lanes through the cup. The deep watches people behind the middles.
The zone described here is called a 3-3-1 zone because there's 3 people in the cup, then 3 people in the middle, and finally 1 person deep. Another standard zone is a 3-2-2. I'll let you figure out that one.
Note: Communication is very important. The top of the cup talks and directs the other people in the cup. The middle-middle directs the top of the cup. The deep directs the middles. The players sitting off help the hammers and warn the deep when someone is behind him/her.