Need Help! Connecting CNC machine to Mach 3

Hi,

I am in the process of building my first CNC machine. The frame is assembled with motors attached. All the electronics and power supplies are attached.

I have watched some tutorials and I have played around with Mach 3 for a while. I think I understand the basics.

When I connect the computer up with the CNC machine, is there anything I have to do before Mach 3 will control the motors? For the moment I just want to see things moving on the machine.

Thanks
Jack