I'm new and I can't view a wml file using Mobile Browser 4.0.

I type a wml file with dotWap 2.0 editor and I save it with wml extension. When I run Mobile Browser and I open the .wml file I just typed it appears me the following error:

WML Encoder: root element not declared (download/alternative DTD failed)

I read in the notes with Mobile Browser I can view wml, xhtml, java ... files, so I would like to know how to view wml contents using Mobile Browser 4.0.