Shut off the power to a device and unplug it, or turn off the breaker switch, or switches to the electrical circuits that the lights, or appliances use. Put a note or a lock on the door to the breaker panel to keep anyone from restoring the power.
Look at the type of terminals your AC rocker switches use to connect wires. Wiring rocker switches involves turning screw terminals, or soldering. The switches will have screw heads, or flat metal lugs with small holes for soldering the wires in place. Loosen screw terminals with a screwdriver, or plug in a soldering iron to heat for wiring rocker switches with soldering lugs.
Connect the hot wire carrying the electric power supply to the input, or common terminal on the rocker switch. The common terminal is typically in the middle of the three terminals, and will be labeled. Wrap the wire around the screw terminal clockwise and tighten the screw, or hold it against the soldering lug and melt a bead of solder over it with the hot soldering iron. Make a bead that's big enough to cover all of the bare wire.
Connect a hot wire from an appliance to one of the outside terminals with solder or a screw terminal. The "on" position for that appliance is with the rocker button flat down on that side of the switch.
Connect the hot wire from another appliance to the other screw terminal or soldering lug. Use the switch to turn on one or the other of these appliances. Turn off both electrical components by leaving the rocker switch stopped in the middle position.