I don't think you fully understand XSLT - it's not really for parsing XML docs (at least not in the traditional sense) - you provide the XSLT parser with an XML doc and an XSL template.
The XSLT parser then maps the XML data to the XSL template (you could use this to turn XML data into an HTML page, for example).
Try Google searching XSL and XSLT for more details.