integrating into website

I looked for an hour for an easy way to do this. Is there a way to easily integrate into a existing website? using something simple like <?php include http://mysite.com/calendar/calendar.php ?>

I have rollovers in my site and when I try to alter the code in the header.php I get nothing, so I am thinking the code doesn't like all those additional java script so something.

This is a great script... One of the best I have ever used. I would just like a simpler integration because I am no php person, I am a designer =)

Thank in advance.