Now you see your waterfall. Adjust the rocks to the effect you want. You could use a few plants though. From your local nursery, you can purchase a varity of water plants. The plants which come in pots, leave in the pot and just add rock to hide the pot.
Reeds usually come in a one gallon black plastic container.
Set the container into the water and add rock for looks. Comfrey grows well if you make a place near the edge of the pond for it. Put a few rocks into the water and pile them so part of the rock sticks above the water line. Nestle the comfrey roots into the spaces between the rocks. Spider lily likes the edge of this pond also.