Uday,
Checkout
the Javaranch XML links page. Start with the tutorials - there are dozens of them. You can also go to
www.google.com and search for "XML tutorial".
Once you are comfortable with the notations, syntax and grammer, you can move on to parsers and integrating XML with Java. Again, the links page above has some good resources for learning about parsers.
Ofcourse, if you get stuck or confused, you can always come here to JavaRanch XML forum and ask questions. I suggest you also browse through some of the old discussions in this forum before asking to see if that issue has been already addressed.
Good luck,
Ajith
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Ajith Kallambella M. Sun Certified Programmer for the Java�2 Platform.
IBM Certified Developer - XML and Related Technologies, V1.