Find a good location in your yard for the composter. It should be at least 4 feet tall, and 4 feet on each side, square. If your clippings pile is smaller than 3 cubic feet or higher than 6 feet, it may not compost properly.
Determine where your four corner posts will be and dig down about 1 foot for each.
Place the posts in the holes, fill up with dirt. Stamp the dirt down as much as possible so that the posts will stay stable.
Nail the planks to the posts.
Lay a thick layer of old leaves or other brown plant debris at the bottom of the composter. This will allow the pile to aerate better when you add your clippings.
Add grass clippings mixed in with other clippings in thin layers.