Lay your four 2-foot boards, parallel to one another and spaced every 2 feet, with the boards resting on their 2-inch sides. Place two of your 8-foot boards on their 2-inch sides, perpendicular to the 2-foot boards, with one long board on each side to resemble a ladder.
Adjust the boards as needed so the 8-foot boards overhang the 2-foot rungs by a foot on each end. Screw two screws through the 8-foot boards and into the 2-foot boards at each intersection to secure the framework of the bench.
Stand each of your 4-by-4-inch boards up on end. Place one 4-by-4 board at each corner of your frame where they can touch both a 2-foot and an 8-foot board. Screw two screws on each touching side through your frame boards and into the 4-by-4 boards to form legs for the bench.
Flip the framework over and stand it on the legs. Lay your four remaining 8-foot long boards side by side over the top of the framework. Adjust the boards as needed to make them flush on all four sides of the bench. Screw two screws through each top board and into the 2-foot frame pieces below at each intersection.
Sand the outer surfaces of your bench to protect against splinters. Apply paint, wood stain and water-resistant coatings as desired to leave the wood with a natural look, or color the bench to make it eye popping or blend in with other outdoor décor.