Desperately need to unlock an Iphone 4

I have had a Droid 2 for several years now, but it no longer works properly (screen will not turn on). My friend gave me his old Iphone 4 to replace it, but its under at&t and we have verizon. My family cannot afford a new phone and we have no upgrades, so its either unlock this Iphone 4 or go dig through the attic for some 10 year phone with missing buttons. Tried looking through this subreddit to see if anyone has already asked this question, but to be honest I have a hard time understanding some of the more technical talk. Sorry if I seem like an idiot.

Edit: its version 5.0.1 with Modem Firmware 04.11.08