The iPad can sometimes be a victim of its own intuitiveness. People find it so easy to use they rarely read the manual, in fact it is not immediately obvious there is a manual. This leads to the issue where if someone can't work out how to do something they just give up assuming it can't be done, or they might miss out on a feature that makes their iPad life much easier.
Upon opening the package that contains your new iPad you will find no paper manual or CD/DVD based manual. Upon using you new iPad you will find no manual electronically stored ready to be used. So where is it?
In fact the manual is on Apple's website, there is a link in safari bookmarks, or if you have installed the free iBook app you can download the iPad guide as a free book. The latter is quite useful as then you always have it on your iPad for reference even if you have no network connection. Of course you might want to read manual on a PC so that you can try things out on the iPad at the same time, in which case the web version is the way to go.
This documentation only covers general iPad usage, for individual apps you will find in the app store that there is a button to take you to the developers website, these often have forums, FAQs etc., and an app will also often come with some form of built-in help or documentation.
If you are still stuck there are a number of other sources of information still available to you (although google is always a good start).
e.g. www.ipadforums.net or apple's own forums.
e.g. iPad and iPhone user.
Many of the smart phone and mac magazines have produced one of glossy specials describing what the iPad can do.
there are a whole raft of books being released for the iPad on various themes. I have seen a dozen or so appear on o'reilly safari book library.
With all the above resources you should pretty much solve most issues.