Verizon iPhone 5 on att go phone?

I have an unlocked iPhone 5 (Verizon). I inserted an att nano go phone sims in the phone and found I get better signal. I want to know the process of using my Verizon iPhone 5 on the att go phone prepaid plan. I was told I could buy the 65$ prepaid plan with att and it would work but I would need to change the apn. Can anyone explain a step by step process on how to set this all up. As I stated, I already have a new unactivated att go phone nano sims card. When I put it in my Verizon iPhone 5, my carrier on the phone picked up att and gave me more bars than the Verizon sims. I mostly stay on Wi-Fi and 3G works better in my area than LTE. So I'm not concerned with which data speed I'm on. I just want to know how to set this up properly and make sure my iMessage will also work.

I owned this web.i've done many unlock if you want to talk to me please add me on skype
oneunlocker.com