Lay the two 8-foot-long boards parallel to each other on the ground, 16 inches apart.
Build your base. Place the two 2-by-6-inch boards at opposite ends and on top of the parallel boards. Make sure your corners are square and attach the boards with your nails.
Nail the five 2-by-2-by-16-inch boards to the 8-foot boards at equal intervals between the 2-by-6-inch boards. Turn your base over when complete.
Build your uprights. Lay two of your 4-foot boards on opposite edges of one of the sheets of plywood and secure them with 1 1/2-inch wood screws.
Lay your remaining two 4-foot boards on opposite edges of your other sheet of plywood and secure them with 1 1/2-inch wood screws.
Attach your two uprights to opposite ends of your base with 3-inch wood screws.
Attach the four 1-by-1-foot plywood boards to each corner of the rack with 1 1/2 inch screws. These boards serve as cross-braces.
Paint or prime your new rack to maximize its life in the outdoor elements.