When you ordered your iPad, you had a chance to get 3G/4G data plan for your iPad. You probably didn't get 3G/4G one. You either didnt get it or didnt order from AT&T, Verizon, or Apple's site. Unfortunetly, you can't upgrade to a 3G/4G model. 3G/4G is a service through a cell phone carrier and costs montly to do. You would have to pay for internet usage.
Ah, makes sense. It was a present so no idea of what was requested. I've got a pay monthly data package from T mobile but just don't know what to do with it.