This is the link to the main Kindle Documentation page:
http://www.amazon.com/gp/help/custom...deId=200317150
There are separate User Guides for the Kindle1 (1st Generation), Kindle-US, Kindle-International, Kindle DX-US, KindleDX-International, KindleDX-Graphite, and Kindle3.
You can download the appropriate User Guide onto your Kindle, onto your PC/Mac, or read it online.