In SMF, everything is driven / processed by index.php. Files with this name is also used as the default startup page when a website / directory is accessed.
If you don’t want to use the forum as the default page and want to write your own, one way is to install the forum in a subdirectory. But if you want to use the same directory as the forum, you can rename the file and write your own index.php.
To rename index.php to [newname].php:
- vi Sources/QueryString.php
- search for $scripturl = $boardurl . ‘/index.php’; – replace index.php with [newname].php