Not my brightest question

[abadsvt]

I want to try my rear suspension but not sure how to hook up everything. I know how the valves work but when you hook up the wires to a switch is what i am confused on. The switch i am using has three conectors on the back. I would imagine that one is for the fill and one is for the dump but what is the center one? Is that ground or power? Also don't you need to have the battery conected to it to give it power? I hope that make sence. Thanks Josh