How do I make an intro for a video?

I wanted to make a YouTube video (more later) and wanted to incorporate a sort of intro animation featuring my web site’s logo. I don’t have any Adobe software (yet) and I use Mac OS 10.6 with iMovie ‘11 (as part of the iLife ‘11 package).
Any help is appreciated, and if you can recommend free software that will do this, please include it in your answer.

ITS AMAZING I found it at http://u96.info/992/adobe-software

Logos 4 for Mac