Error Pages
Creating custom error pages (flash tutorial)
In this section of cPanel, users have the ability create custom error pages for their site. The most common errors are displayed on the front page for users to select from. Each section will take the user to an editor where they can edit the custom error page right from cPanel.

click image for better view
The five most common error codes that are displayed in this section can be seen from the above picture.
400: Bad Request
401: Authentication Required
403: Forbidden
404: Wrong Page
500: Internal Server Error

As seen from the above picture, users have an area to edit the error page to include anything they like. Along the top of this editing box there is a list of buttons, each button corresponds to a function that can be included into the file. Remember that cPanel saves all the error pages as .shtml web pages.
Referring URL: Displays the URL that referred a user to the page.
Visitor's IP Address: Displays the users IP address.
Requested URL: Displays the URL requested by the user.
Server Name: Returns the servers name or websites URL.
Visitor's Browser: Displays information about the user's browser.
Redirect Status Code: Displays the error code associated with the error.
Save as: Users can save the file under a different file name if they'd like.