How to create a form?

Okay, I must be blind (and dumb). I see this cool formS thing in Numbers, but cannot find anything in the help to explain how you create an input form or manage it/them. Can anyone point me in the right direction? I mean, the tutorial that comes with iPad Numbers shows you an input form example, but I can't find the reference in the help on how to do it.

Thanks, and I,m sure I,ll be embarrassed when I find out how obvious it is!