To start working  with xml  most important thing to do
is to disregard all the hypes around it. XML is more
or less some delimited ASCII text data  that follows
w3c standard.

Now what you can do with ASCII text with known
delimiter can be done with XML data as well. Good
thing about xml is that there are some tools and
technologies available for you to use freely.

If your xml is complicated use apache xslt processor
(www.apache.org) to access  data from xml using xsl
program. Otherwise you may like to use some xml
parser(comes with j2sdk) to get a DOM structure and
find the data from the dom tree node. You will come to
know about more tools and technologies such as SAX,
XSL:FO etc.

If you send me your xml structure and tell me what you
want to do with them, I will be able to help you
further.