Loosen and remove the bolts from the existing metal bedframe using a wrench. Take the bolts out of both sides of the headboard. Place the nuts and bolts aside so you do not lose them.
Attach a modi plate bracket to the left side of the headboard using the hardware that comes with the kit. Position the bracket over the existing holes on the front of the headboard, and insert a bolt through the holes. Tighten the bolt and add a nut, if included, in the modi plate bracket kit. Repeat the process with a second bracket on the right side of the headboard.
Hold the headboard upright. Slide the headboard against the attachment brackets on a metal queen-sized bedframe. Line up the holes in the modi plate bracket with those in the end of the bedframe. Insert one of the original bolts through the hole. Pass the bolt from the back of the bedframe through to the front. Twist a nut onto the bolt, and secure it with a wrench. Repeat the process with the remaining bolts and nuts.