How to Change an Electrical Switch
Step 1: Make sure that the electric current to the outlet is cut off by going into the circuit breaker that feeds the switch. This is an absolute must to prevent electric shock.
Step 2: Remove the outlet cover plate by unscrewing the two screws to expose the inside of the light switch.
Step 3: Use a voltage tester to test for power going to the switch.
Step 4: Remove screws placed at the top and bottom used to hold the switch in place. They need to be removed in order to 
pull out the switch from the box.
Step 5: Label each of your wires accordingly before disconnecting the switch using colored twist ties or writing on strips of masking tape.
Step 6: Loosen the terminal screws, pull off the wires, and remove the old switch.
Step 7: Determine the type of switch you have and verify that the new switch is the same type (single-pole, 3-way, 4-way.)
Step 8: Place each of your labeled wires in their proper position and tighten the terminal screws. Should a piece of wire break during this process cut an 6 to 8 inch strip of wire and connect it to the original using a wirenut and then connect it to the terminal screw.
Step 9: Install the new switch back into the switch box, connect the screws to the top and bottom of the switch, make sure that no bare wires are coming into contact with anything outside of the switch box.
Step 10: Replace the light switch cover, return power from the circuit breaker, and then test your newly installed switch.
