screw, or you can place it threw the back wire hole that is on the same side of the switch as the silver screw.
the hot (black) wire is connected to the brass screw or you can place it threw the hole in the back of the switch on the same side as the brass screw. keep in mind that this wire also is red sometimes.
the ground (bare copper or green) wire, if the device has one sometimes they do not, attaches to the green screw terminal on the switch or to the electrical box.
first you will want to turn the power off to the switch that you are replacing at 