I just bought my second iPad, so I'm not quite new to it. However, this second device is 3G capable. My first was not (and now, with the release of iPad 3, you can get a bargain on the first gens quite easily). I joined this forum last year but never had any real cause to use it. Now I do because I'm trying to locate information on how to activate the 3G. I found a post in Google search...anyway, that's why I'm here.
Do you have the AT&T or the Verizon version? Oh, and are you in the USA? There are a couple of ways to activate the 3G (in the USA - I am unsure about plans not in the USA). Here's how to activate an AT&T account in the USA, maybe the Verizon one is the same?
1) Go to your Settings > Cellular Data and turn on the cellular chip. Then, press on the View Account tab. If you don't already have an account, you create one. After giving your payment information, you should be good to go.
2) Call the carrier (or visit them on the web) to open an account. Then, once it's activated, you can turn it on via the Settings app, just as in step one.
One thing to remember is that you are buying data on a by-monthly basis. If you do not stop the purchase, the carrier will automatically bill you for another month. So, it's a permanent thing until you turn it off.
Hope some of this is helpful. Do let us know how you get on. Oh, and if you already found out how to do all this, then all I can say is "yay, and welcome back!"
Marilyn