What elements are necessary for a contract, law homework help

Please define (1) A contract, (2) An offer, (3) valid acceptance, (4) consideration. 

What elements are necessary for a contract?  What forms may consideration take (how can it be made)?  Does a contract have to be in writing, or what makes a valid contract?  What is a the statute of frauds?  Who can make a contract, and who cannot?  What is an implied contract?  How does an implied contract differ from an express contract?