The 'iPad User Guide' can be found in the iBooks app for free as previously mentioned, and I found two additional 'FREE' iPad books in the iBook app. One is titled, "iPad Starter Guide" and another book is titled, "iPad Basics".
Also, after you load the free iBooks app, you can drag-and-drop the iPad PDF manual that you downloaded from the previous post directly into the iTunes 'Books' section and sync it with your iPad. Then it will appear in iBooks app when you select the PDFs at the top left in the iBooks app.