Prepaid with unlocked V551

I just bought a unlocked V551 without a SIM to use for prepaid service. I
thought about using T-mobile prepaid. What do I have to do to start using
prepaid cards ?? Also, can I or can I not access the T-Zones on my V551 ?
What's this I hear about having to 'reflash the firmwear', and how do you
get that done ? So far, I think I just brought on alot of aggrevation for
myself.

Thanks for any help you can give me.