cPanel is the most widely used web hosting control panel in web hosting. cPanel has over the years developed several ways to  support it's users including the step by step video tutorials which can be found within the cPanel control panel in the preferences section. The video tutorals are great for answering most basic to mid level questions about how to use the control panel.

In addition cPanel has a terrific wiki area where you can search for documents on how to do higher level applications within cPanel:
http://twiki.cpanel.net/twiki/bin/view/AllDocumentation/DocsIntro

There is also a forum for cPanel users and moderators to ask how to questions for cPanel use:
http://forums.cpanel.net/