How do upgrades on cell phones work?

I have a iPhone 6. Last week, I accidentally dropped my phone in the toilet. It is probably dead. I have to use a replacement iPhone. My carrier/ISP is Sprint. I'm 20. Can you explain to me how cell phone upgrades work?

Since we don't know if you have a post paid and paying monthly payments on the phone or prepaid account, which you have paid up front for the phone or if you are on a regular contract, or some sort of promotional contract or a grandfathered plan that is just month to month now.

You call them up, tell them you need a new phone and ask what your upgrade options and terms are for your contract/account and they will tell you how you can go about upgrading your phone (and maybe also the plan), to get a new phone.

I don't have the same phone plan you do, but at mine, an upgrade involves trading in your *working* phone in order to pay less than list price (and often a really large discount) for a new phone so long as you renew your phone plan contract at that time.

I don't know if you will qualify for an upgrade with a ruined phone.

What does damaging your phone have to do with upgrades?