I can still try to give you pointers, though. But French is hard... >.<

Basically, though, you use imparfait when you describe something if it's to say you were doing an action when suddenly, something else happened (in passé composé).
"J'étais sage." -> description. Implies you may still be wise.
"Je mangeais une pomme lorsque le téléphone a sonné." -> normal action then something happens.

As weird as it may be, passé composé is a tense you use when describing an action that happened in the present or the close/immediate past. For example, you would say "J'ai oublié mes clés." if you realized just now you forgot your keys.
If you use passé composé to describe something, it gives the feeling the action that happened was unusual didn't happen a lot.
"J'ai été sage." ->implies you were a good kid for only a short period of time like few years max or it could be a day. In that case, it's better to precise the duration of the action. "J'ai été sage avant d'atteindre l'adolescence."

I'd also say passé composé is used if you, as of now, are thinking back on your past years (using it on all your text will give it a reflective feel) and imparfait is used if you or anyone was describing the past (it would seem more factual)...
I don't know if it makes sense...
This is why I'm not becoming a teacher. XD

Omo! Sorry I did not see this before... I am native French speaker so don't be afraid to ask my help. ^^

Did you still need help? :P

write one for both ways and then turn the one thats right, lolol
ok no.

...you want to eat a French desert? how about a yogurt parfait?

/slapped: sorry, I take Chinese so uh bye