Locate two studs in the wall with a magnetic or electric stud finder. Make a pencil mark on the wall to indicate the locations of the studs.
Place the standards for the shelves on the wall on top of the pencil marks. Set the standards where you want them to hang on the studs. Set a level across the top of the standards to ensure they're level with one another. Hold a level against the sides of each of the standards to ensure they're level against the wall. Make pencil marks in each of the holes along the back of the standards.
Remove the standards. Drill holes in the wall over each of the pencil marks.
Set the standards back on the wall so the openings are over the holes you created. Drill a 2 1/2-inch screw through each of the holes in the back of the standards.
Attach the L-shaped brackets into the grooves on the back of each of the wall-mounted standard where you want the shelves to hang. The L-shaped brackets on each of the wall standards should be parallel with one another.
Set the shelves on top of the L-shaped brackets. For added security -- if the bracket is thick enough -- drill a vertical hole in each L-shaped bracket, about 2 inches back from the front of the bracket. Drive a 1 1/4-inch screw up through each hole in the brackets and into the shelves.