|The method of customising error pages (such as the ones displayed when the HTTP server returns 404 Not Found or 403 Forbidden) differs depending on if you have a Linux site or a Windows site.
For cPanel users, you can set this up in your cPanel control panel, or using the method below.
For all other users, create a file named .htaccess in notepad (or similar text editor) containing lines in the form:
ErrorDocument 404 /errors/notfound.html
You can add extra lines defining different errors, for example:
ErrorDocument 403 /errors/forbidden.html
After creating this file, upload it to your root FTP folder.
Make sure the error pages you have defined exist on your server as well.
You will need to define HTTP error codes in your global.asa file. The following website may be of some help http://www.devhood.com/Tutorials/tutorial_details.aspx?tutorial_id=639