This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
There is no point in somebody here telling you what JMX is about. That is precisely the kind of question to be answered by googling. After you spend an hour or two reading through those results, and you have a more specific question, please post it.