Start by looking at the resources FIRST provides, located here:
http://www.usfirst.org/roboticsprogr...control-system
First you'll see two wiring diagrams. These show you how to hook everything up for power and data - very important!
Next, there's a link to the benchtop testbed. As a rookie team, go through this and do everything exactly as it's listed! This will give you the confidence that you can actually get everything up and running before you start doing stuff like adding more motor controllers.
Once you've had some testing/experience with the system, come back on here and ask more questions!