Lay the frame pieces out on the floor in the order they are to be assembled. Make sure the lips on the side rails face into the center of the frame.
Hook the keyhole mounts onto the bolts protruding from the legs of the headboard. Repeat, hooking the mounts to the bolts on the footboard. Alternatively, thread a washer onto each bolt, and screw the bolts through the slots in the frame rails and into the bolt holes on the headboard and footboard. If the bolt goes all the way through the frame thread a nut onto the other side, hold it steady with an adjustable wrench, and tighten the bolt with a screwdriver.
Place the center support across the center of the bed. Fit the notched edges into the lips on both bed rails. Line up the bolt holes. Thread a washer onto each bolt ,and screw the bolts through the holes to secure the center support. Thread a nut onto the bolt from the bottom, hold it steady with an adjustable wrench, and tighten the bolt with a screwdriver. Screw or unscrew the center slide until it reaches the floor and supports the rail.
Place the box spring on top of the rails. Make sure the box spring rests on the lips of both rails. Place the mattress directly on top of the box spring.