The new iPad requires itunes 10.7 or later. iTunes 11 is the latest version. Are you running a current version of iTunes on your computer?
iTunes 11 has a different interface than previous versions. To make iTunes 11 look more familiar use the View menu in iTunes 11 and select View Sidebar. You should see your iPad, when it is connected to your computer, listed in the sidebar like always.
Aside from what Ralph suggested - which I think is the best thing to do - you should see your device in the upper right portion of the iTunes screen - even if you do not have the sidebar enabled.
This might be helpful for you as well if you are Windows.
If you are Mac....
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Apple - Support - iPad - Syncing