Slide a stud finder from one end of the recess to the other. Mark the location of each wall stud that is nearest each end of the recess with a pencil.
Measure up from the floor with a tape measure and mark the wall at 18, 36 and 54 inches at each stud marking. Hold a level across each pair of measurement markings and draw a straight line across the wall with a pencil. This is the line marking for each shelf.
Lay the hardwood boards on a work surface. Apply an even coat of wood finish to each board using a natural bristle paintbrush. Allow the finish to dry for at least four hours and apply a final coat.
Position the six hinged folding shelf brackets over the stud markings where they correspond with the height markings. You should have a pair of brackets at 18, 36 and 54 inches going up the wall. Drive the screws that were included with the brackets through the mounting holes into the wall studs using a screw gun to fasten them to the wall.
Center a board over each pair of folding shelf brackets. Drive the screws that were included with the brackets through the mounting holes into the bottom of the shelves using a screw gun to fasten them in place.