How to turn off 3G off on the iphone 4s?

I know this is gonna be a little long and i'm sorry!
I'm on going on vacation to Greece and i want to bring my iphone because i heard imessage is free when using Wi-Fi (right?) so i wanna bring my phone so i can text me friends! But what if i bring my phone to the beach to take pics and they text me? I wouldn't have Wi-Fi so wouldn't that cost me extra? (btw i have verizon) is there a way to turn off 3g or cellular data or something so it wouldn't cost money because my dad would flip out!

Put your phone on airplane mode or try to find a near by Wi-Fi source.

There's a place in your settings where you can turn off cellular data