Turn off power at the source
Verify the circuit is de-energized with a tester
Identify the switch terminals
Strip the wire ends
Connect the power source wire to the common terminal
Connect the load wire to the output terminal
Connect the ground wire to the ground terminal if required
Tighten all terminal screws securely
Insulate any exposed conductors
Mount the switch in the panel or enclosure
Restore power and test the switch operation