If you are a fast learner, I recommend the site www.java2s.com (Java API by Example).
Here's the full link for the concurrent package: http://www.java2s.com/Code/JavaAPI/java.util.concurrent/Catalogjava.util.concurrent.htm
EDIT:
If you can spend some cash (and isn't in a hurry), I recommend this book:
Java Concurrency in Practice
http://www.amazon.com/Java-Concurrency-Practice-Brian-Goetz/dp/0321349601/ref=sr_1_1?ie=UTF8&qid=1290021702&sr=8-1
It is really full of examples and good practices.