HOW DO I ADD A GROUP POLICY TEMPLATE TO MY EXISTING AD

I AM USING THE DEFAULT GROUP POLICY TEMPLATES FOR ORGANIZTION UNITS IN WINDOWS 2003 DOMAIN. (RIGHT CLICK TO PROPERTIES, SELECT GROUP POLICY THEN EDIT OR ADD EXISTING GROUP POLICY.

HOW CAN I ADD ITEMS TO THE GROUP POLICY TEMPLATE? E.G.
THERE IS ONE WHERE YOU CAN HAVE THE GP COPY A FILE DIRECTORY TO WORKSTATINGS. CALLED COMPUTER SETTINGS\PREFERENECES\FILES. BUT I DO NOT KNOW HOW TO ADD IT.

THANKS