These words are common enough that it's possible I'll miss a few usages, but I can tell you some of the basic ones.
"Will" is used to describe events in the future.
"I will go to school tomorrow."
"It will rain next week."
"Would" is sometimes used in certain kinds of questions. It's used to ask about someone's willingness, interest, or ability to do or get something.
"Would you like to a cookie?"
"Would you be willing to help me with my homework?"
"Would" is used for things/situations which could have happened but didn't.
"I would have gone to zoo yesterday, but it rained." (If it had not rained, I would have gone. But it did rain, so I never actually went.)
"If he'd asked me out, I would have said yes." (He did not ask me out, so I did not say yes.)