How to redirect to index.php?

When people go to mysite.com, I need them to be redirected to mysite.com/index.php. One of the modules that I am using has an issue on the homepage unless it is at mysite.com/index.php 

You do this from the web server. If you are using Apache, by default it will look for the first file named index.html, then others.

Look for "DirectoryIndex" in your Apache config and change it to index.php, then index.html. Reload/restart Apache and you should be right to go.