How about a flash tutorial on how to create WebSphere Portal Themes?
How to Create A Theme for WebSphere Portal Sometimes that link only works with Firefox. For IE, you might want to try this link:
Alternate link for WebSphere Portal Skin and Theme Development The tutorials show the fundamentals - they don't use a rapid development tool like IRAD. I think this is the best way to learn. Once you know the basics, you'll see the real benefits of the wizards in IRAD.
Enjoy!
-Cameron McKenzie