Wiring a double wall switch is no more difficult than wiring a single switch. As long as you keep the wires for one light separate from the wires for the other, you should not have any problems. This tutorial is designed to tell you how to install or replace a basic switch. Any electrical work in which you need to go into the wall itself should be handled by a licensed professional.
Turn off the power to the room you are working in.
Remove any existing switches from the wall box.
Attach the wires for the first light to the screw terminals on one side of the switch.
Attach the wires for the second light to the screw terminals on the other side of the switch.
Attach the copper ground wire to the switch ground screw.
Turn the power back on and test the switches before screwing the switch to the wall box.