This week's book giveaway is in the OCAJP forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide 1Z0-808 and have Jeanne Boyarsky & Scott Selikoff on-line! See this thread for details.
There are any number of XML APIs you could use: SAX, DOM, XPath, dom4j, XOM, JDOM, StAX... If you haven't used any API, try out a few to see which you like best.
I probably wouldn't start with SAX, though, it requires more code to be written than most of the other APIs. XPath might be a good fit if you want to extract a few specific, well-defined values out of a document.