Find the wall studs in the area where you want to mount the wall table. Use the stud finder and mark the place where each stud is with the pencil at the approximate height you want your table. Choose two studs, around 16 inches apart, to mount your table on.
Mark the exact height of your table in a horizontal line between the two chosen studs.
Align the shelf brackets, with the 18-inch end pointing down the wall, and the right angle one inch below the table line. Make sure the brackets are straight. Screw them into the wall and the stud behind the wall.
Center the table top over the shelf brackets. The table top can be MDF board, plywood, or a pre-fabricated table top. Make sure the back edge of the table is flush with the wall. Screw the brackets onto the table top from the underneath up.