Place the wooden countertop flat on a work surface with the top side facing up and the long back edge facing you.
Drill a 2-inch hole through the countertop in the center of the long back edge of the countertop using a drill equipped with a 2-inch hole saw bit. Space the hole 1 inch in from the long back edge.
Sand the edges of the hole with a fine-grit sanding pad until they are completely smooth. The hole will allow wires from accessories such as computers, printers, phones and electronics chargers to be neatly channeled down through the back edge of the desk.
Apply two even coats of clear spray lacquer to countertop. Allow the first coat to dry for 4 hours and apply a second coat. Wait 24 hours for the second coat to dry before continuing.
Turn the countertop upside down on the work surface so that the bottom side is facing up. Align one metal table leg in each corner of the countertop. Space the mounting plates on the legs 1-inch in from the edges.
Drive the mounting screws that were included with the table legs through the holes in the mounting plates into bottom of the countertop with a screw gun.