Locate studs in the wall behind the bed where you want to install the headboard with a stud finder. Studs are usually spaced 16 to 24 inches apart, so locate the studs that correlate with the width of the headboard. Mark the studs with a pencil to identify the location before you start drilling mounting brackets into the wall.
Drill the lower mounting brackets to the wall and into the studs. Once installed, use a level to ensure both brackets are even.
Drill small holes into the back of the headboard then screw the brackets into each corner with a drill or screwdriver. Measure the width of the brackets on the wall with a measuring tape so you know how far apart to space the brackets on the headboard to ensure they line up.
Slide the brackets on the headboard directly down onto the wall brackets. Use a level to check that the headboard is even, or adjust if necessary.