Draw the outline of the desktop on the plywood sheet, using a pencil and ruler, using the dimensions you've chosen for the finished desk.
Cut out the desk surface with a table saw. Remove splinters from the cutting with sandpaper.
Locate a single wall stud in the wall where you want the the bracket for the desk to to be installed. A 20-inch bracket holds the folding desk, and is attached to the middle of the folding desk. Place the bracket vertically on the wall so the wall stud is directly behind the bracket. Check the vertical placement with the level.
Install the wall bracket to the wall stud by drilling 2-inch-long screws through the holes in the wall bracket into the wall stud; hold the bracket in place on the wall as you install it.
Open the folding bracket so that it is fully opened. Place the desk surface on top of the bracket’s top surface. Attach the desk to the bracket by screwing in small screws through the bracket’s installation holes with a handheld screwdriver. Use at least six screws, three screws on each piece of the bracket.