Lay the plywood sign down so the backside is facedown. Place one post underneath the sign at each end. If the sign is larger than 45 inches in length, place an additional post in the middle of the sign for support. There should be one post every 15 inches.
Hammer nails into the plywood sign so the nails extend into the sign posts. Repeat this step for each post until the posts are securely attached to the board.
Stand the sign up. The sign is ready for use.
Horizontally slide the stud finder along the wall on which you want to hang the plywood sign. Stop when it lights up or beeps; make a mark with a pencil.
Place the plywood sign against the wall to determine where you can drill holes in the sign to match the marks made on the wall. Make pencil marks on the plywood sign to indicate the places.
Drill holes through the sign at the marks. Insert a 3-inch screw into each hole and place the board against the wall. Use the drill to attach the sign to the wall through the wall studs.