My name is Glenn Davidson and I too am a newbee to JBoss and MySql. I have just figured out how to connect the two together. Please remember that I am a newbee also......
Go to the docs/examples/jca directory and you should see a mysql-service.xml file. You will have to make a few edits to this file and then copy it to the server/default/deploy directory. There are instructions within the mysql-service.jar for you to add some information to the server/defaults/conf/login-config.xml file. Make those changes also. Read the instructions carefully as several different "properties" need to have the names the same. It was that simple. If you run into trouble I'd be happy to give whatever help I can. My e-mail is email@example.com. Your e-mail will end up in my junk folder to start so please make the subject stand out.