No need to get frustrated, we'll sort this out real quick.
Click here for the diagram
#2 clips onto the door frame. Using a table knife or something similar (nothing sharp) remove #2. This will expose a couple of #8 screws that hold the handle. Remove the screws. Put the new handle on and secure with screws. Put #2 back on. You should be good to go.
Here is a short clip that shows how to remove the inner door panel on most microwaves. Hope it helps.
Let us know how it turns out...