Apply a paint stripper to the door if there is paint that you want to remove. Allow the paint remover to sit and scrape with a putty knife. You can paint over it, just check that the existing paint is water based if you are painting with water-based paint. Repeat the application of paint remover and scraping until the paint is gone.
Fill in any dents, dings or holes with wood putty applied with a putty knife. Allow the putty to dry and sand with a hand sander until level with the rest of the door.
Paint the door with the primer and set aside to dry.
Paint two coats of paint and allow ample time between coats for drying.
Flip the door over when dry and measure 4 inches down from the top edge close to the side and mark with a pencil. Repeat on the other end of the door.
Place one D-ring on the mark just made and install with the included screws. Line up the screw hole over the mark so each side is even. Repeat on the other mark.
Thread the end of the picture wire into the D-ring leaving 4 inches extra to secure the end of the wire. Loop the end of the wire back through the D-ring, and bring the tail of the wire into the loop just made. Pull the wire tightly and wrap the tail around the rest of the wire. Repeat with the other D-ring cutting the wire 4 inches longer than the distance to the D-ring.
Measure the door and transfer these measurements to the wall where you want the headboard. Find the center of the distance and make a dot with the pencil. Find the center point between the center dot and the outside measurements and make a dot on both the left and right of the center point.
Drill a pilot hole at each dot.
Insert a drywall anchor by tapping with a hammer until flush with the wall.
Install drywall screws into each anchor leaving three-quarters of an inch of the screw out of the wall.
Hang the headboard on the screws the same as you would hang a picture by balancing the picture wire on the screws.