Cut three of the 2-inch-by-4-inch boards in half, producing six 4-foot boards. These will form the frame of the hutch.
Lay two 8-foot 2-inch-by-4-inch boards parallel on the ground, resting them on their narrow sides. Use one of the short 4-foot boards to connect them as the third side of the square. Use a carpenter's square to check that the right angles are true; then nail them together using at least two nails in each corner. Repeat the process to produce another three-sided frame. These will form the top and bottom frames of the hutch.
Lay one of the frames on the ground and nail one of the four remaining 4-foot 2-inch-by-4-inch boards to the inside of each of the corners, using the square to check that the right angles are true. You should now have the three-sided frame on the ground with four vertical supports rising at right angles from the four corners. Turn the whole thing onto its side and nail the top frame into position.
Use the three large sheets of plywood to cover the sides and top of the frame. The small sheet will cover the back of the frame, forming a three-sided box with a roof. Make sure that all joints are sound before attempting to move the hutch into its final position.