What do you do with an unlocked cell phone?

What do you do to get service on it?
Yes You are absolutely correct . If a phones is said to be an unlocked, it can be compatible with any other GSM carriers internationally .

How do i go about getting some sort of wireless provider to use the phone with?
Unlocked phone works with all GSM carriers world-wide .But, it doesn't works with CDMA carriers .

Can someone just explain to my how these phones work?

A phone which can be compatible with all other GSM sim cards are said to be an unlocked phone .

Unlocked phone :
If your phone is unlocked, you can insert another network sim card with it and use it without any interruption . For example : If your phone is tied with AT&T, you cant use T-mobile with it . Whether your phone gets unlocked from AT&T or from any of the online vendors like ClassicUnlocking.com , your phone works with T-mobile and other GSM sim cards ....