Place the headboard against the wall first, adjusting it to the height that you want it above your mattress. Draw a line across the top of the headboard, directly on the wall. This serves as a loose guide.
Turn your yard stick vertically and measure 12 inches down from the top of that line. Mark the 12-inch-mark with a pencil. Now turn the yard stick horizontally against the mark you made. If your headboard is 60 inches wide, make a mark every 5 inches across the length of the wall. This is where you will mount your brackets.
Screw the brackets onto the wall first at each 5-inch mark using a screwdriver and screws. If you have drywall you can hammer or screw drywall nails or screws.
Turn the headboard over so that the back faces you. Using your yardstick, measure 12 inches down and 5 inches across the width of the back of the headboard. Attach the matching brackets in the same way you attached them to the wall.
Hook the headboard brackets into the wall brackets.