This clip shows you how to replace a regular toggle switch with a dimmer switch on a light. It is easier than you think according to the presenter. There is a box with a green ground wire and two black wires. In dimmer switches, it doesn't matter which way you connect the two black wires; they are interchangeable. Turn the power off. Then unscrew the switch once you have opened the plate. Then you simply connect the two wires to the two wires on the dimmer switch. The presenter shows you exactly how to do it with a real example.