Disconnect power to the microwave. Simply unplug from the wall or turn off the breaker in your fuse box.
Open the microwave door. With the flat-head screwdriver, pry off the plastic panel from the inside of the door. Be careful not to break the panel in the process. The two screws securing the door handle to the microwave are located behind this panel.
Unscrew the two screws securing the door handle, then remove the handle. Align the screw holes on the new door handle to the screw holes on the door, then insert the screws and secure the new handle.
Snap back the plastic panel into place, then restore power to the microwave.