Place the 1-by-8-by-24-inch hardwood board flat on a work surface. Position one 2-by-2-by-6-inch hardwood board in each corner of the shelf board. The 2-by-2-inch ends should be flat against the shelf board. These are the legs.
Lift up one leg at a time and apply wood glue to the end of the leg and the area of the shelf board that it touches. Press the legs in place against the shelf board and immobilize them using wood clamps. Wipe off the wood glue that seeps out from the joints with a damp cloth. Allow the wood glue to dry 24 hours and remove the clamps.
Apply two coats of wood finish to the shelf assembly using a paintbrush. Allow the first coat to dry at least four hours before applying the second coat. Wait 24 hours after the final coat before continuing.
Rest the shelf assembly upright on a work surface. Drive one decorative head wood screw through the top of the shelf board into the center of each leg using a screw gun. The screws will add a decorative touch to the surface of the shelf and also reinforce the legs.