How do you change the rear signal light bulb on 2002 Volkswagen beetle?

Open the hatch. Right behind the light fixture that contains the bad bulb is a cover plate inside the trunk. Remove it and reach inside. You'll find two big plastic nuts that hold the fixture in place. Remove both (they turn with the hand) and push the fixture out of the fender. Unhook the wire to the bulb, twist the socket to get it out, change the bulb, put the socket back in and reconnect the wire, put the fixture back in, put the nuts back on and replace the cover.