Structure
I'm not sure what you mean by "structure?" The structure of a short story is the same as the structure for a screenplay. Only the manner of writing is different. In a short story, you include narrative that you leave out of a screenplay. You just have to read a bunch of short stories. There is no other way to know how to write one.
Technically, a short story iis from 2,000--7,500 words. Under 2,000 is a short-short, and from 7,500--17,500 is a novelette.
There's really a huge difference between a short story and a novel, and the difference is far more than simply length. The only real answer is to read as many short stories as you can find that are in whatever genre you wish to write in. Reading many short stories is the only way to learn how to write one.