VOR:
(note the linked films on the right)
NDB:
http://www.youtube.com/results?searc...20explain&sm=3
ADF:
And then again, as I told you last year already
, the lessons in the section "Navigation" of FSX's own library, in German it is called "Ausbildungszentrum". You find the option on the left of the main screen of FSX.