Unplug the microwave power cord from the wall receptacle. Turn the microwave around so that you can access the rear of the unit.
Look for the access cover on the upper right corner of the microwave. Four screws secure the access cover to the microwave. Remove the screws with a Phillips screwdriver.
Press the bulb inward gently with your fingers, and turn it counterclockwise to remove it. Insert the new light bulb. Turn it clockwise to secure it in the socket.
Place the access cover back over the rear of the microwave. Secure it with the four screws.
Position the microwave back to its working location. Plug the power cord into the wall outlet.