Error pages are served to Internet users when any one of a variety of errors occur, such as when a user enters an incorrect URL or is not authorized to access a specific directory in your web site. Companies often customize error pages to brand them with a specific corporate image and a link to their home page. You do not have to customize these pages - the error page is always available, whether customized or not.
To create or modify a customized error page:
Click on the Error Pages link under the 'Advanced' header in Cpanel.
Click on the button of the required error page, such as the 404 button.
Enter the HTML code for the error page. You can use the buttons at the top of the page to insert variables into the displayed code.
404 Not Found
The requested page, ,is not available.Click on the SAVE button. Your page for the selected error should now appear as your custom page.