Philippe,
In that case, you should talk to your NSC again (assuming your are an end-user). If you have the license to create reports, your NSC should provide the training material(s) as a service. If you want to be trained it's normal to be charged, but the manuals should be free (IMHO). If Navision Belgium doesn't have the Application Builder training manual, then they should find a way to obtain it from the Dutch Navision website for you. There it is, as an PDF file of some megs (145 pages in all).
Good luck.
John