Short story submission - scenes

How do you break apart scenes when submitting a short story?

Here's one of my problems. Let's say you have a story. The first part is narrative summary, and the second part is an immediate scene. Is that two scenes or one? In other words, do you add the "#" symbol in between the summary and the immediate scene?

I'll give a quick example:

(summary)
Jimmy was a poor boy. He ate out of the trash can almost every morning for breakfast, and for lunch he was lucky to fry up a dead pigeon, which he'd usually find in a park, in an iron skillet over a dumpster fire.

His parents were both dead, taken out in a plane crash. After the incident, Jimmy was sent to a foster home but ran away two years ago. Now, Jimmy didn't have a home. The streets of LA were his home, only the side walk and the passing cars to look after him now. . . .

(immediate scene)
One day, Jimmy was in the park, looking for a pigeon, and saw something shiny in the distance, buried beneath a bed of fallen leaves. He walked over to it and picked it up. It was a diamond ring. The ring shone brightly and reflected the sunlight seeping through the treetops. Jimmy's eyes grew big, and he quickly stuffed the ring into his torn, brown trousers and looked around to see if anyone had noticed. . . .

Is this one scene or two? By the way, this story was written for the sake of brevity, and usually both sections would be much longer.

I don't think there is any particular rule about this. In your example, perhaps because it is so short, I would treat it as one scene. If your story is very long, you could even have chapters (although I would only use chapter numbers if there were three or more chapters). And it's also possible to separate scenes like this with a line of asterisks or pound signs as you suggested (i.e., #######################).

I've seen published authors employ all of these techniques. My own preference is to not use separators unless absolutely necessary, but it's really up to you and what you think looks best and reads best on the page.