Cut a piece of plywood that measures 24 inches in length and 41 inches in width with a circular saw.
Cut a piece of 1-inch upholstery foam the same dimensions as the plywood sheet with a serrated knife. Depending on the size of the roll of foam, it may be necessary to cut several pieces to get the size required.
Place the plywood sheet on a flat work surface. Apply spray adhesive to the plywood, keeping the adhesive can 6 inches above the plywood and passing it back and forth to get a thorough coating. Place the foam onto the plywood. Line up the edges so they are flush. Press the foam down into the adhesive and let it sit for 30 to 45 minutes.
Cut a piece of fabric that measures 34-by-51 inches. Place the fabric face-down on the work surface. Place the foam-covered plywood on top of the fabric.
Pull the fabric up and over the sides of the plywood. Staple the center of the fabric to the back of the plywood. Do this with all four sides of the plywood then pull the rest of the fabric over and staple it to the back of the plywood. Trim away any excess fabric.
Attach four picture-hanging rings to the back of the plywood. Position each ring 2 inches below the top edge of the plywood and secure them with 1-inch wood screws. Space the first two screws 2 inches in from the right and left edges. Place the other two screws 12 inches from the left and right rings.
Pre-drill a pilot hole into the wall where you want to hang the headboard, 47 inches off the ground. Use a handheld drill equipped with a 1/4-inch drill bit. Measure and drill three more pilot holes at the same spacing as the rings on the plywood.
Insert a wall anchor into each of the pre-drilled holes by pushing the tip of the anchor into the hole until the other end is flush with the wall. Screw a 2-inch screw into each of the wall anchors. Twist until 1/2-inch of the screw remains outside the wall. Lift the headboard to the wall and slip the rings onto the screws.
Set a twin-sized bed frame in front of the headboard. Place the box spring and mattress onto the bed frame.