Move the stud finder from left to right on the wall. When the stud lights up "red," it has found a stud. Mark the stud in the wall with a pencil.
Find an additional stud behind the wall. Studs are spaced every 16 to 24 inches. King headboards are about 4 feet long. Make sure both marked studs are within 4 feet of each other.
Place a flush mount flat against the wall, on top of one of your marked studs. Make sure the flush mount is facing up.
Insert a screw into one of the flush mount holes. Use an electric drill to screw it into the wall. Then screw the second screw into the flush mount.
Repeat the process to install the second flush mount to the wall.
Measure the exact distance between the two wall flush mounts.
Measure and mark this distance on the back of your king headboard.
Screw in two additional flush mounts to the back of the headboard using the electric drill. Make sure the flush mounts are on the marked spots, and are facing down.
Ask one additional person to help you pick up the king headboard. Hold it against the wall, and force the headboard's flush mounts to slide inside the wall flush mounts.