when i should use " passe compose et passe simple"

Answer 1

Passe compose is for a single action that occurred in the past: J'ai vu un oiseaux = I saw a bird (only once).

Passe imparfait is for a repetitive action that occurred in the past: Je voyais un oiseaux chaque matin = I saw a bird every morning.

Passe simple is the past tense that is only used for writing literature, so you would meet it in books.

Answer 2

In general, if you are using the passe simple, you are talking about things that happened in a more distant past. This tense also tends to be used more in literature than orally. Not that you can't use passe simple when you are speaking to someone, it just isn't as common (at least in France) to express a past event or action as it is to use the passe compose. For instance, if you went to the store earlier today, you would probably use the passe compose. On the other hand, if you are talking about one time that you went to the store when you were five years old, you might use the passe simple. Hope this helps.