Lay the waterbed heater down on the decking of your waterbed. Place the heater in the middle of the bed, closer to the foot than the head.
Run the wire through the corner gap between the frame and the waterbed's decking.
Connect the waterbed heater controller to the side of your waterbed frame with an electric screwdriver and wood screws. There is no right or wrong place to connect the controls, as long as it is easy for you to reach to make adjustments.
Plug the wire from the heater into the connector. The connector is located on the bottom of the controller.
Place the vinyl safety liner over the top of the heater, insert the waterbed mattress and fill your bed with water.