I just finished dealing with this battle. First the code that was provided to you from Carson (first reply) is crucial to load your flash movie into your website. Follow his instructions and you will easily be able to add flash movies.
Now for creating the content. There is a couple of options. I used iWorks '08 Keynote to create a flash introduction. Basically you can create a slide show with animations and then convert it to Quicktime. You can either use the Quicktime file as a movie insert or convert the Quicktime to a flash file. Please note that the export to flash feature within Keynote will remove alot of your slide transitions and animations. Thus, if you want flash you should export it to Quicktime to keep all transitions and animations. Then you can use Adobe Flash C3 to convert it to flash or any other flash converter software (such as the products sold from the link posted above).
If you want to get a little flashier there is a software called The Ad Creator (
http://www.flashadcreator.com/)
This software has about a 100 templates for flash introductions. It is meant for companies but you can easily adapt it to your personal website by adding photos and changing captions. I just bought it but have not done anything yet on my website.
You can view a sample introduction made from Keynote and then converted to flash on my website.
http://web.mac.com/brademcee/Site/WeintraubFamily.html
Hope this helps!