How to swap or upgrade my iPhone 4S?

To keep it short:
-I have a two year old iPhone 4S
-it doesn't have enough storage
-my brother thinks I should trade it in for a 5c
-I've heard of the Apple Trade-In program but am wondering how you would do that/do you keep the information from your old phone
-also how does your phone plan affect this process? (We have Sprint)

-this is America. Nothing is free in America. America is about making money so you will not be able to 'swap' a 4s for a 5c and not pay additional cash unless the trade-in program is still running. See below.
-I have two 4s that are 2.5 years old and a 5 that's about 2 years old. I have a 3GS that's 4.5 years old. What is your point?
-Storage? Well, delete something off the phone and store it in iTunes for use later. Clear out text messages from 5 months ago, delete that app you thought was cool but really stinks that you've only used once. Delete some voicemails, Take songs/movies off you haven't used in months, if ever.
-Buyback program is to help recycle old phones so they don't end up in landfill somewhere. Check the store to see if the program is still running. They pay you but you'd better off selling it yourself. See here.
http://appleinsider.com/articles/14/05/09/apple-boosts-iphone-44s-trade-in-values-in-iphone-upgrade-push

http://appleinsider.com/articles/11/08/09/apple_offers_buyback_program_for_old_iphone_ipad_macs

http://www.gazelle.com/new
-Well, if you are eligible for an upgrade on Sprint, then it can be $99 plus your parents signing a new contract. If you are not eligible, you will not get that phone at the contract price of $99. You will have to pay the full expensive price of roughly $500 and up.
Bottom line, if your contract isn't up, and your parents won't sign for it, then don't worry about it and save your money for later. Best luck.