Level the ground where you plan to locate your pool, if necessary. If there is no perfectly level spot on your property, use sand to fill in the low side. Pour the sand into place and tamp it down until you have created a level area for your pool. This step is essential. If the ground the pool sits on is not perfectly level, the pool will lean to one side, and the weight of the water will eventually cause the walls to collapse.
Set the ground cover on the spot you have created for the pool. The ground cover protects the bottom of the pool from imperfections such as rocks and protruding roots that could otherwise damage it.
Lay the pool out on top of the ground cover. If you have an inflatable pool, the entire pool is in one piece, and you simply inflate the ring at the top of the pool and start filling it with water. The pool walls rise as the pool fills with water.
Place the bottom of the pool on the ground cover if you are using a metal-framed pool. Attach the metal sides of the pool according to the manufacturer's instructions. The basic process for attaching the side panels and filling the pool are similar, but they vary somewhat from manufacturer to manufacturer.
Attach the filter to your pool according to the manufacturer's instructions. Connect the filter hose to the input on the pool. Plug the filter into an outdoor electrical outlet, but do not turn on the filter yet. Install the filter cartridge if it is not already pre-installed.
Start filling your pool with water and watch closely as it fills. If the level of the pool water looks uneven relative to the sides of the pool, that means the ground it is sitting on is not level. If that happens, remove the water from the pool, disassemble it and re-level the ground.
Turn the filter on after the pool is filled with water. Check the filter to make sure it is functioning properly.