Template with terms

Hi all,

I am newbie and I need to create a letter.  When the user selects a particular case status, a warning letter addressing the customer should be created.  The users will print it to send it to the customer.  No email is necessary.  I don't know how this functionality works.  for instance, do I have to create a trigger through the AAF?  and also, when the user changes the status, is the document displayed then at that point he/she would print it through MS word, is this possible?  we want that result, rather than storing the letter in a sever.  Based on what I have read, I would have to