Next, we'll move onto the side panels of the cabinet. While we're building these panels out of plywood, one could easily use glued-up hardwood panels for a much more elegant look.
As noted in the plywood cut diagram on page 5 of the free woodworking plans you downloaded in step 1, we'll be cutting two cabinet sides, two identically-sized shelves (unless you anticipate a lot of weight on the shelf above the drawer, in which case you'll want to check the note in step 8) and a couple of support pieces.
Begin the cutting of the sheet of 3/4" sanded plywood by cutting the two cabinet sides, which are two pieces at 32" x 23". Then, cut a notch out of one corner measuring 3" in height and 3 3/4" wide (see page 2 of the detailed drawings). This notch can be cut most easily using a jigsaw and a Layout Square
Next, cut two shelves measuring 34 1/2" x 22 1/4". Set these aside for the moment.
Finally, cut out two support pieces from the remaining plywood: one measuring 35 1/4" x 12", and the other measuring 35 1/4" x 5 1/2". These will be used as backs to support the structure of the cabinet.
Before moving onto the next step, cut a piece of 1x4 at 34 1/2" in length for the top piece on the face of the cabinet.