CPG Dragonfly™ CMS

Create your welcome page and save it as index.html
Copy your existing index.php to a new file called main.php
If you're using DragonFly 9.0.6 edit config.php and change $mainindex to main.php
If you're using DragonFly 9.1 go to Admin -> General -> Main Settings -> config.php and change Index file to main.php
Oh, and delete index.php afterwards!
(this all assumes your webspace is configured to use index.html if index.php can't be found and you don't have access to it's configuration file to change it)