I want to ask how to install a template file to the right-click-->Create Document?
Must create a directory in your home named Templates and put inside a empty document of each type you wish to use, for example , for html template open your favorite text editor and put this:
<html> <body> <h1> </h1> </body> </html>
then save this file in $HOME/Templates/html , now you can chice this template in contextual menu.
It works well now.
And I am very sorry to say that the XFCE can't set the Templates directory by ourselves.