>> My son is all motivated to learn Java so that he can hack around in Minecraft, so I'm looking for ways for him to get
>> started. I have no coding background either, so I am equally lost.

>> Can anyone recommend something to get him to the next stage?

This will help you and your son through a simple and practical approach while learning the Java Programming language.
http://www.tutorialspoint.com/java/index.htm

Online Java Compiler
http://www.compileonline.com/compile_java_online.php

Useful Tool: http://www.compileonline.com/

Another very useful online tool: http://ideone.com/

Good luck with the journey and welcome to the coders world :)

Aruna