Code:
ErrorDocument 404 /filenotfound.php
Now, you want to create a new page, called 'filenotfound.php' and add this code to it.
Code:
<?php define('IN_MYBB', 1);
require_once("global.php");
add_breadcrumb("404 Error", $_SERVER['PHP_SELF']);
eval("\$page = \"".$templates->get("404")."\";");
output_page($page);
?>
Now, upload the filenotfound.php file to your main website's directory.
Then, create a new template on your main theme with the name 404 and add this to it:
Code:
<html>
<head>
<title>Your title</title>
{$headerinclude}
</head>
<body>
{$header}
Your 404 Page Content
{$footer}
</body>
</html>
Edit where it says Your 404 Page Content to whatever suits your needs.
Not my content don't come to me if shit doesn't work but it should