Slide on a pair of work gloves and safety glasses to protect your skin and eyes. Turn off the power to the room you are working in via the main circuit breaker often located in your home garage or basement.
Unscrew and remove the face plate on the existing outlet or switch. Pull out the existing plug or switch from the junction box.
Unscrew the existing plug or switch screws to loosen and remove the junction box wires. Snip off any frayed wire ends with your pliers and remove 1 inch of plastic sheath from the tip of the wire to expose fresh copper wire.
Look at the three wires --- black (hot), white (neutral) and green or copper (ground). Crimp the ends of all three wires into small one-eighths-inch loops with needle-nose pliers.
Loop the green or copper wire around the green screw inside the junction box. Tighten the screw. Loop the black wire around the brass screw on your toggle switch. Tighten the screw. Loop the white wire around the silver screw. Tighten the screw.
Fit the toggle switch back into the junction box. Screw on the cover plate. Turn on the power from the main circuit breaker before testing the switch.