Explain to me how this works? (iPhone)?

So i have the iphone 4s 32gb which i bought on launch last year. Which means i have a year left on my contract. If i wanted the iphone 5 how would that work. Like say i sell the 4s. Would i use that money to pay off my contract and then pay an additional $199 for the new phone. Will it reset my contract? Will i even be able to get the iphone5? I hav the 2gb data plan.

?2012-09-19T00:28:33Z

See if u can upgrade or trade in or accidentally break ur phone I hope u have insurance