Cut the banana into coins 1/2" to 3/4" thick. Set out a wrapper, run a wet finger along the edges to wet them (sort of like an envelope flap, but all the way around), put a banana coin in the center, draw two opposing corners together so they meet over the banana. Fold the two other corners similarly and press the edges down to make a tightly sealed package. If corners stick out from the thing, pinch them to make sure they are sealed and won't let oil in.

When the oil is hot, put the rangoons in with the folded side upward. This is improtant - you want the thinner side to cook first, otherwise as the air inside the rangoon expands it can weaken the wrapper, allowing the cooking oil inside. When one side is golden brown - which takes maybe a minute - turn it over, cook until that side is golden brown, and then place the rangoon on paper towels and blot with more paper towels to drain off the oil.

You can add extra stuff to add to the taste of banana. I've used cinnamon and honey - separately or together - and would recommend them. However they aren't necessary; just by itself the banana tastes like fruit pie filling.