Determine the size of the above-ground pool you plan to buy, including the height of the walls, the water depth, and the length and width of the deck that rims the pool walls.
Add the extension length of buttresses, which extend from pool walls diagonally and support the walls from the outside, to the length and width of the total pool surface size. The extension length is the distance from the pool wall that the buttresses extend at their bases.
Lay out and mark an area in your yard that is 4 feet longer and wider than the total area of your pool with the buttress extension lengths added in. Make your measurements with a tape measure and hammer 2-foot wooden stakes into the ground with a rubber mallet to mark the corners of the pool site.
Wrap twine around the stakes that outline your pool's site, pulling it taut and adding additional stakes as needed. Spray paint the entire pool site outline on the dirt or grass using the straight lines created by the twine as a guide. Remove the stakes and twine.
Hire a backhoe and operator to excavate your pool site. Ask that the hole be dug to a depth that is 1 foot less than the depth of the water in the pool.
Assemble your pool within the hole, following the manufacturer's instructions. In most cases this will involve erecting the walls, spreading sand for the pool base and installing a liner. Attach the pump, plumbing and electrical connections. Fill the pool with water to the recommended depth.
Fill in dirt around the pool using a garden spade once it's filled with water. Bury the buttresses and fill in the 2-foot-wide trench around the pool that comes from the feet you added when you marked the installation site.
Connect the pool to the pump and filter system, which can be set up anywhere in your yard. Clean the pool as needed using a pool vacuum or skimmer net, but don't drain the pool for cleaning or during the winter.