Brent,

Here is doc on how to stack them:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/hardware/installation/guide/HGcliSET.html

After stacking them login and make one of the switches master by giving it a higher priority. Priority is between 1 and 15. So I would give the master 14 or 15. I usually give priority to members too like:

Switch-A 14 (Master)

Switch-B 12 (member)

Switch-C 10 (Member)

Switch-D 8 (Member)

Also make sure you have the same image on all of them.

HTH

Reza