Place the hinges at the corners on the bottom side of the desktop. I forgot that I planned to allow a one inch overhang from the last step. The hinges as shown here are set in from the ends of the desktop too much. When I finished the stand up desk, the ends of the vertical supports did not clear each other. I later had to move the hinges out a bit on each side. Drill holes that do not quite go through to the other side and insert the screws.