Measure the length of your fabric-covered headboard. Measure the width of your headboard. For example, say the length is 60 inches and the width is 60 inches.
Place the measuring tape length-wise across the top of the headboard again. Using a fabric marker with disappearing ink, make a mark at every 5 inches. Move down 5 inches and stretch the tape measure across the length of the headboard again. Make a mark every 5 inches. Continue doing this until you reach the bottom of the headboard.
Insert a staple on top of every marking. The staple will make a dimple in the fabric.
Hot glue the buttons on top of the staples.