in mach choose Output1 or 2, or what ever you want to be your spindle on relay, an M3 and or M4 could turn it on, m5 will turn it off.
ports and pins, goto outputs, go down to the output you chose for your spindle out put, put in the correct port your using 1 or 2, and send to the output pin on your hobbie cnc board that you have your spindle on wired into.
scott