Unfortunately, we do not have and I do not know of a downloadable tutorial for the Nvigation system in your car. Do you have the original owner's manual? That seems to me to be the place most likely to have the information.
Should list 3 reference guides, two of which are NAV:
22156264621 2002 AUDI NAVIGATION QUICK REF GUIDE ENG $5.00
22256264621 2002 AUDI QUICK REF.GUIDE NAV. SYSTEM $5.00
Not sure if they have a customer service number so you can talk to someone about the guides to see if they actually apply to your vehicle... but for $5, I'd just order them and see what shows-up in the mail.