http://www.sdl.com/en/globalization-..._beginners.asp
(just complete the form and you get the link to download the webinar)
It's a webinar for Trados 2007 beginners: (useful anyway for the other versions)
Introducing translation memory
How to get started with SDL Trados 2007
Remember first to download the webex player from here
http://support.webex.com/support/downloads.html
You won't regret it!