Behemot Prolog can load program only from the current directory.
This manual section supposes that you know how to use a prolog interpeter. In the next versions will be added an introduction for novice. A good book to learn Prolog is :
Ivan Bratko
Prolog
Programming for artificial intelligence ( second edition )
Addison Wesley
Standard prolog and Behemot prolog
Predicates specific to the graphics editor
Programs and examples