Empty out all the water and all the objects in the pond. Let the pond dry for two days to ensure there is no water left.
Place the flexible pond liner in the pond. Push the pond liner in all the corners so the liner is touching the bottom of the pond. Leave excess pond liner hanging on the outside of the pond.
Fill the pond with water. Ensure the ends of the excess pond liner do not fall into the pond.
Place rocks or structures to hold the excess pond liner around the perimeter of the pond.
Cut the excess pond liner that you cannot cover with rocks or structures. Use the utility knife to cut the excess liner.