On line Help for Keynote / Numbers / Pages on the iPad - http://help.apple.com/iwork/1.2/safari/interface/#tan72234385. Want to learn more? - Try the "Apple Training Series" Books. The books have written "how to's" as well as a video DVD, that helps you learn Apple applications for your iPad at your own pace. You can find out info. about this book at - http://www.peachpit.com/search/index.aspx?query=iPad.
To learn how to get documents from your Mac or PC computer to the iPad, or from the iPad back to the computer, for use with Pages, Numbers or Keynote - see http://support.apple.com/kb/HT4088.
Also check - http://www.apple.com/support/ipad/ - click on the topic you want, in the left column for info on those topics. For the iWork applications, select the help link for more info.