Measure out the desired distance for the gate and mark the best location for the two posts. Shovel out a hole at each marking, making the hole 12 inches deep, and 4-by-4 inches wide. Layer 4 inches of gravel at the base of the holes.
Set a 56-inch metal post in each hole and fill in the hole with concrete up to within an inch or two of the top of the ground. Let the concrete sit overnight.
Drill through one of the posts 6 inches from the top, making the hole all the way through the post, parallel to the position where the gate will be installed. Slide a j-bolt hook and strap hinge into this hole and tighten it in place with the included nut. Repeat to add an additional hinge about 2 feet lower than this one on the post.
Measure the distance between the two metal posts. Subtract 1 inch to allow for smooth rotation of the gate on its hinges. Cut six 1-by-6-inch boards to this measured length. Set the boards on the ground with their long, thin sides touching. Position three 1/2-by-3-by-36-inch boards perpendicular to them, with their large sides touching. Drill two holes through each 3-inch board and into each 6-inch board. Attach the boards together with 1-inch wood screws to form the gate.
Position the gate between the posts and up against the j-bolt hook and strap hinges. Drill through the hinge attachment holes and into the gate and attach the hinges to the gate with 1-inch wood screws.
Position a latch between the other post and the other side of the gate and attach it in place by drilling 1-inch wood screws through the attachment holes and tightening the other part of the latch around the post.