What animal (s) and plants to add and substrate?

I bought this tank with the cut foam years ago. it has a water fall feature. The water pools are shallow and I threw some water plants in there recently and some small pieces of moss. I have larger pieces of pillow moss I just bought also. Should I put any type of substrate over the foam? I also have not decided on what type of animal to put in once its established. I also was going to get a timer mister or raining device. Could use any input/ideas and what you think for animal(s). I was thinking dart frogs. lm not sure the exact size but its 20inches wide and about 11 inches deep. The height is about 9 inches with the foam and 12 without it at the highest point on the lower area. The 2 pools of water, one is about a 1/2 inch deep and one is about an inch maybe a lil less. They are both very small. I can cut them out more if needed.