I am a beginner in XML.Can somebody help me how to create a search on a xml

I have retrieved the records from the database in the form of xml.now i would
like to create a search on the fields or tags in xml.any sample code will
be helpful/any site which discusses similar topic.

I have retrieved the recordset from the database in xml form . and I would
like a <a href...> for the Url field retrieved how do i do it.Kindly help