They should fit together like jigsaw pieces.
How to hang up a wall mirror.
See step 7 above in hang a mirror using hooks for information on how to install drywall anchors and how to remove unwanted drywall anchors.
Hold your mirror up to the wall to see how much space it will take up.
Place a scrap piece of wood that is approximately half as long as the mirror is wide underneath the hanging wire on back of the frame.
Make sure you have enough space on the wall for the mirror and otherwise decide how you want it positioned relative to other items on the wall and in the room.
Hold the mirror against the wall at the desired position.
Find a place to hang the mirror.
Use anchors if the bottom cleat isn t lined up over wall studs.
Gradually reduce your hold on the mirror until it is fully supported by the cleat.
Note if you ve used wood glue to secure the mirror s cleat be sure to wait until the glue is completely dry before hanging the mirror.
Mark the location of the top edge and the center of the frame.