What do i do if i buy a new phone?

Soon I'm planning on buying a new Iphone 6 on Amazon.com. It is also going to be GSM unlocked. So let's say I do buy this phone, what would I do next when it comes in the mail? How would I hook it up to my carrier? (verizon) Can I even hook it up to my carrier? I'm just wondering if it's possible or not possible, and if it is what do i do?
Thank you to anyone who genuinely responds.
(ill reward best answer…)

You should show all your friends that you do indeed belong in their elite circle of self indulgent, entitled people. Yey for you!