Measure the width and depth of your desk. A hutch will generally be as wide as the desk and a third of the depth of the desk. The height depends on how many shelves you want to have. When choosing lumber, 1/2 inch thick pine in one foot by eight feet boards should work well. These can be stained or painted to match or coordinate with the desk and the decor in your room.
Cut two pieces of lumber to the height you want your hutch. A basic hutch might be two feet high with with two horizontal shelves placed at heights of your choosing. These pieces will be the two uprights at either side of the hutch.
Measure and mark the position for the shelves on the interiors of your two uprights based on what height you want your shelves. Drill two small pilot holes per shelf on each upright. Drill the holes approximately two inches from the front and back edges of the uprights.
Insert the zinc-plated angle shelf supports into the uprights. One zinc shelf support has a load capacity of 25 pounds, and these are be sufficient for holding the shelves in place firmly.
Cut the 1/4 inch plywood to the size of the hutch. This is the height of the hutch by the width of the hutch. The plywood forms the rectangular backboard of the hutch.
Staple the backboard to the backside of the two uprights.
Place the uprights and backboard on the desk and slide the shelves in place.
Cut a small hole in the base of the backboard to allow computer and other wiring to be run down the back of the desk. This is not necessary if you use wireless equipment.
Once you are satisfied with your construction, you can take the hutch into the garage or outside in order to sand and paint or varnish it. Allow any treatments to dry thoroughly before finally positioning the hutch on the desk.