Yeah, you're not getting that info by calling, let alone this forum. You have an internet connection, Google it. A search that took less than 5 seconds pulled up a how to guide quicker than it took you to post this topic.
Also carriers are only required to let you use your phone elsewhere, not flash anything because you don't like your old carrier's boot screen.
PS: A Verizon SIM card isn't going to do you any good on another carrier. I dunno why you are requesting unlocking help for that. Having worked for Verizon, you would have known you don't use Carrier X's SIM to use Carrier Y's service.