Turn off power to the outlet in which the GE Spacemaker microwave will be plugged into to avoid electrical shock. Find the breaker on the main electrical panel and shut it off. If necessary, turn off power to the side or whole kitchen.
Find and mark the wall studs with a stud finder and a fine point marker. Run a stud finder over the section of the wall that the rear of the GE Spacesaver microwave will abut and draw dots vertically.
Hold the rear mounting plate against the wall. Match-up the rear mounting plate with the studs and push the tip of your fine point marker through the mounting plate's pre-drilled holes. Remove the mounting plate and drill pilot holes into each mark with a 3/16-inch drill bit.
Place the mounting plate against the wall, aligning it with the pilot holes. Secure the plate to the wall with a Phillips-head screwdriver. Tape the top mount for the GE Spacesaver microwave to the bottom of the cabinet which it will be mounted under using the included mounting tape. Drill holes into the cabinet bottom following the specific instructions included with your GE Profile to run the power cord and fan exhaust.
Pick up the GE Profile microwave and hold it into place, then push the power cord up through the bottom of the cabinet. Do not plug the appliance in, but keep the cord in place while sliding the microwave up and back into position. The Spacesaver will catch the clips on the mounting plates as it is slid into position.
Drive in the self-aligning screw through the bottom of the cabinet into the top of the Spacesaver microwave. Read and follow the manufacturer's instructions for attaching the exhaust; this will vary by year.
Turn the power back on at the main electrical panel. Fill a glass with water and test the GE Profile microwave by heating it.