Choose an area that doesn't have too much water flow from rainfalls. If you cannot find a proper spot, provide drainage before building your foundation. Contact a plumber, contractor or pool supply store to see if there is anyone in your area that can provide this service if you are not familiar with the process.
Clear an area that is about 4 feet larger than the circumference of your pool. Dig out the ground with a shovel and use a leveler throughout the area to make sure it is level. Place 2x6 lumber planks and place joints at each intersection to form a squared foundation.
Place a cinder block inside the foundation area where each pool post will be resting and layer the inside of the boarded foundation with pea gravel, and then sand. Make sure the sand and cinder blocks are flushed with each other, and then rake another layer of pea gravel over the entire area. Use a leveler to check that the foundation is level before assembling the pool.
Place a plastic liner or specialized padded liner over the foundation area. Assemble your pool per the manufacturer's instructions, making sure that each post is resting on a cinder block.