THE PILOT-IN-COMMAND (PIC) FAILED TO PROVIDE ADEQUATE SUPERVISION WHILE TRAINING THE COPILOT AND ALLOWED THE AIRCRAFT TO ENTER A STALL/SPIN, THEN DID NOT PROVIDE ADEQUATE REMEDIAL ACTION TO PROPERLY RECOVER FROM THE SPIN. FACTORS RELATED TO THE ACCIDENT WERE: USE OF EXCESSIVE ELEVATOR TRIM, THE PIC'S LACK OF TRAINING (IN APPROACHES TO STALLS) AND LACK OF EXPERIENCE IN THE MAKE/MODEL OF AIRCRAFT, AND THE COPILOT'S LACK OF RECENT EXPERIENCE IN THE MAKE/MODEL OF AIRCRAFT.