Hi
XML is unfortunately not like other office document formats where if the document has the right extension it will import
For you to be able to import an XML file the correct fields with the correct names need to be in the correct places
If your intention is to load the GL and other data, i would suggest that you rather use rapid start services in NAV 2013, you can find a lot of info here and rapid start is a lot easier to use if you haven't worked with XML before
Search for Rapid Start in NAV 2013, then go check out this like for how it works
msdn.microsoft.com/.../hh179428(v=nav.70).aspx
Cheers
Nev