prepositions - When should I use "when" and "while"?

But you can't find anything while you're crying.
But you can't find anything when you're crying.

I'll tell you about it while Frank saddles the horse.

I'll tell you about it when Frank saddles the horse.

When should I use when, and when while?
Are these sentences correct?

Answer

When used to mean "during the time that something is happening," while is synonym of when.

While I was waiting at the bus stop, three buses went by in the opposite direction.

All the sentences you wrote are correct.