Turn off the power to your range top at the breaker box. Remove the range hood from the range top (consult range top documentation if necessary). This will expose the wire needed to power your over-the-range microwave.
Disconnect the wall plate from the back of your Whirlpool microwave. Position it in the location where you want it.
Hold the wall plate in place and put a level up to it.
Adjust it as necessary until it is level, mark the spots for the anchor holes with a pencil. Use a screwdriver or power drill to connect the wall plate to the wall.
Measure the distance between the bolt holes on the microwave. Drill the microwave bolt holes in the bottom of your cabinet with the power drill. If necessary, insert some small wood blocks (only if the cabinet is recessed) before drilling the holes.
Drill a 1.5-inch hole in the location on the cabinet where the power wiring on the microwave will be. Lift up the microwave (get help with this if you need it) and route the wire through the hole.
Secure the microwave in its spot by hanging it on the plate and then connecting the bolts to the microwave through the bolt holes you drilled in the bottom of the cabinet.
Open the microwave door and place the level inside it to make sure it is level. Connect the power wiring to the wire coming out of your range hood.
Close the range hood, turn the power back on, and then program your new Whirlpool over-the-range microwave.