How can I add a custom made error page?

You can use .htaccess to show your visitors a custom made error page, instead of a standard server returned error code. The most common errors to create pages for are:

Page Not Found (404) 

Forbidden – Access Denied (403)

Add the following code to your .htaccess file:

ErrorDocument 403 http://one-example.com/forbidden.html
ErrorDocument 404 http://one-example.com/notfound.html

Replace http://one-example.com/forbidden.html and http://one-example.com/notfound.html with the location of your custom made error pages.