Spread the pool liner open and allow it to sit in the sun for about 1 hour. The sun heats up the liner and makes it easier to install the aluminum framing.
Slide one larger-diameter aluminum pole through a sleeve in the pool liner's top edge. Connect a T joint to the end of the post. Slide a second pole through the next sleeve and connect it to the T joint's other end. Push a second T joint on the second pole's opposite end and insert a third pole into the next sleeve. Continue to work your way around the pool.
Place a narrower aluminum side wall pole vertically through a loop on the pool liner's side wall and through the restraining rope. Squeeze the pins, located at the pole's top edge, into the pole and slide the pole into the T joint. Release the pins so they pop out and lock into the T joint's holes. Move on to the next T joint and install another aluminum pole in the same way, until all T joints have aluminum poles extending from them.
Lift a narrow aluminum pole about 2 inches off the ground. Slip an end cap onto the pole's bottom edge and lower it to the ground. Repeat with the remaining aluminum poles.
Hold onto a larger aluminum pole, at the top of the pool frame, and give it a gentle shake. Repeat this in 1 or 2 other locations to ensure that all poles fit snugly together.