OW, if you lift the liner about 10 " around the outside so the edge of the liner is suspended of the bottom then take a piece of cardboard and cover the skimmer hole, you can insert a shop vac hose into the return hole and leave it hanging clear of the sand bottom it will suck every wrinkle out of the bottom. Turn the water on and start filling. As the water level rises lower the liner slowly and a little at the time and the liner will fit like it was painted on. I have installed 20-30 per year for the last 20 years. We got so that 3 of us could do 2-3 per day, but we had a bobcat and a laser transit, and knew just what tools to get out of the truck before we started.
Later, Nat