Assemble the four wood stretchers so that you have a rectangular frame. The ends of the stretchers should interlock and slide together.
Set the frame on the floor or another flat surface. Lay the fabric on the frame, centering it on the frame.
Pull the ends of the fabric to the back of the frame, pulling the fabric as tight as possible.
Staple the fabric to the back of the frame in the center of the top stretcher. Staple the fabric on the back of the frame in the center of the bottom stretcher, then in the center of the left stretcher and finally in the center of the right stretcher.
Keep the fabric taut and continue to staple on the four sides of the frame, working from the center of each stretcher out to the ends. Space each staple about 2 or 3 inches apart.
Unroll the string of lights. Find the outlet nearest the bed so that you know which side of the headboard to start the lights on.
Place the start of the string of lights (the end without the electrical plug) on the side of the headboard furthest from the outlet. Put the lights on the inside of the frame, just below the fabric.
Staple the lights to the inside edge of the stretchers. Do not staple through the lights. Instead, the staple should hug the wiring. Continue to staple the lights to the frame until you reach the side closest to the electrical outlet.
Cut a piece of picture hanging wire that measures 1 foot longer than the width of the bed. Staple the ends of the wire to the back of the frame, in the center.
Hammer two nails into the wall, 20 inches above the bed. Space the nails equally apart.
Hang the lightbox headboard from the nails, looping the picture wire over the nails. Stretch the plug end of the lights out from the back of the lightbox and plug it into the outlet.