To install a microwave above a stove, secure the mounting plate to the wall below the cabinets, and drill holes for the microwave vent and mounting screws. Lift the microwave onto the mounting plate, secure it with screws through the top cabinet, and make the necessary electrical and ductwork connections.
The manuals for over-the-range microwaves often include paper templates to facilitate measuring, marking and drilling holes. The mounting plate can also be used as a template if a paper one is unavailable for the wall.
Locate and mark the wall studs. Position the mounting plate so that the required holes align with as many studs as possible, and mark the location of each hole. On the wall, draw a vertical line to mark the center point of the cabinet above the microwave.
Tape the paper template to the bottom of the cabinets above the microwave, or measure, mark, then cut the designated holes. A recirculating microwave only needs holes for mounting screws and the electrical plug. A top-vented unit requires additional holes for the vent in the cabinet bottom and wall inside the cabinet. A horizontal exhaust oven needs a hole in the wall behind the microwave.
Once all of the holes are pre-drilled, install the mounting plate on the wall with wood screws or toggle bolts, if needed. With help, lift the microwave onto the bracket, and thread the plug through the coordinating hole in the cabinet. Secure the top of the microwave with screws through the bottom of cabinet.