You might want to check this past post: http://www.biztalkgurus.com/forums/viewtopic.php?t=2
It talks about some good ways to start to learn BizTalk.
Also, the BizTalk Help Guide has a 2 part tutorial that is good as well.
If you go to a Launch Event, you will get a VPC with BizTalk 2006 all set up with 10 or so labs.
Best of luck.