Decide on the dimensions of the desk, keeping in mind the height you need to sit comfortably and the ideal length you need for a workspace.
Cut a hole out of the center-back of the plywood desktop area, measuring 3/4 inches in depth and two inches shorter than the total length of the desk. A jigsaw is an ideal tool for this cut as the blade is small and can be fit into tight spaces.
Saw the ends of the 1-by-4-inch desk legs so that they are parallel to the floor when set at 75 degrees.
Trim down two 1-by-4-inch boards so that they are a total of six inches long using a saw. Make a 75-degree cut out of them so that they fit flush with the legs. Using strong wood glue, secure these board cuts to the corners of the surfaced 3/4-inch plywood desktop so that the back edge is flush with the back of the plywood and the 75-degree cut is facing the front.
Apply the same glue to the front edges of the board cuts and fit the legs into place. When the glue has set, turn over the desk and screw two 8-hole corner brackets into the 90-degree intersection of the legs and desktop using 1/2-inch screws to secure the desk area and the legs.
Cut a 1-by-6-inch board to the total width of the desk and glue it to the tops of the legs and rear board cuts. This, along with the board cuts and the rear part of the desktop, finishes the open storage area of the desk.