How to set a data limit on my iPhone 4s?

I just recently got an iPhone 4s and my Ma wanted me to set a data limit on it. I don't know how to do this though, and haven't found any results when I searched for it. I have Verizon if that helps… IOS 6 too.

There's no data limit in IOS 6. There's however a way you can monitor how much data you have used this month. Just press on Settings, then Generals, then Usage. Then Cellular Usage on the bottom.

Hope this helps