Remove any previous hardware that you don't think will be needed for the new office space. Plug/Fill any holes that are not needed, sand, and paint if needed.
Measure up from the ground for the placement of the desktop table top (the average height of a desk is 28" - 30"). We measured up 27 1/4" ( 28 inches desired height , 27" to the top of the support 1 x 4, 3/4 inches to account for the thickness of the 1 x 10 that will be placed on top.
Tack the Laser Cube at 27 1/4"and level it out so it reflects across the other side of the closet. Using the Ryobi Whole Stud Finder located and mark out all of the studs across the closet. Repeat this step and the desired location for the upper shelf.
Measure out the dimensions across the closet and sides and cut the 1 x 4 to length. Hold the 1 x 4's just above the previously marked studs, so you can align were the studs will be placed, and pre-drill the 1 x 4 to mitigate splitting of the wood. Using a level screw the 1 x 4 inch pine boards to the wall using the 2 inch cabinet screws. Repeat this step all the way around the closet walls and in the location for the upper shelf.
Lay the 1 x 10's across the top of the 1 x 4's, ensuring they are level. Screw them into place, top down. Repeat the last two steps if you want to add a shelf for storage.