This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
There is not a method in this class to set the background image for a JPanel. You will probably have to override paint() in your JPanel to achieve this. You may get some ideas from this discussion on Sun's web site.