When you install phpwcms there is an index.html page in phpwcms root. This is only a simple phpwcms info page that links to the login.php. If you want to use a simple index.html or default.html this is no problem. Webserver configuration can handle different index pages, but will load them in different order. Often it is configured like this: 1) index.htm/html, 2) index.php and so on.
Create your index page like you would; visit phpwcms project website index page
Put this peace of code into your own index page. That's all you have to. If you find a better solution for handling this please post it.