Chaoticspeed

i didnt get any instructions with the kit so i'm kinda confused as to what to attatch the wires to. there are the 3 gauges each with a wire coming off of them with a little connector on each end. these attatch to the connectors on the wires coming from the little black box that came with the kit, but there is 4 connectors on the box. is this not used or what? also there is a black wire and a red wire coming out of the box.. i assume that this is ground/power, but what do i connect them to?