XML to XML transformation using BI Publisher (Fusion Financials)

Hi, This is related to XML transformation related to Fusion financials. We have a requirement to transform the XML generated for Wire payment using BI publisher reports. The standard XML generated by oracle payment format is very elaborate. One of our customer's bank is looking at a much smaller XML with limited fields. I was notified that a similar transformation (XML to XML transformation) can be achied usined XSLT templates in BI publisher.  I would like to understand the detailed steps to achieve XML to XML transformation using BI publsiher. Thanks a lot for your assistance on this topic.