Locate and mark the studs where the supports will attach to the wall and measure the distance between the studs. Use this measurement to mark the location for the notches on the shelves; the center points of the notches should be the same distance apart as the wall studs. Cut the notches in the shelves using the method above.
Mount two of the legs on the wall by driving screws through the notches and into the wall studs. Make sure the legs are plumb and the notches line up perfectly before attaching them to the wall.
Line up the notches on the shelves with the notches on the legs and force the shelves into place. It may be necessary to tap the shelves with a rubber mallet to mount them properly. Once the shelves are in place, fit the notches in the other two legs over the notches in the shelves.
For a finished look, sand the piece and rub it with tung oil.