Put the two pieces of 1-by-8-by-39 3/4-inch oak lumber on a worktable so the long edges touch and the ends are even with each other. Measure from the end of one and make marks at 9 3/4, 10 1/2, 19 1/2, 20 1/4, 29 1/4 and 30 inches. Place the framing square on the marks and draw lines across the width of the lumber.
Drill three pilot holes midway between the lines with a 1/16-inch drill bit. Drill another three holes 3/8 inch from the ends of the two pieces. Keep the holes 1 inch from the long edges and center the third between the long edges. These are the sidepieces to the DVD shelf.
Apply glue to the ends of two of the 1-by-8-by-15-inch oak lumber boards. Place them between the sidepieces at the top and bottom. Be certain the lines drawn on the sidepieces are facing each other. Secure them with 4-penny finish nails. Use a damp cloth to clean up the excess glue squeezed out when assembling the pieces.
Run a bead of glue on the ends of the remaining 1-by-8-by-15-inch oak lumber. Set them between the lines drawn on the sidepieces and secure them with 4-penny finish nails.
Glue the exposed 3/4-inch edges of the sidepieces and the shelves. Put the 16 1/2-by-39 3/4-by-1/4-inch oak plywood on the DVD shelf and secure it with 2-penny box nails. Turn the DVD shelf over and clean up the excess glue with a damp cloth. Sand the inside and outside of the DVD shelf with 100-grit sandpaper before applying a finish.