Thanks Rich,
Yes that printer is connected directly to the Server PC, and if anyone wants to use that printer he ist have to login to server. for this admin of Server has to give a username and password. what i want is that anyone who is on our network can use printer without logging on to Server PC.
About changing security tab of printer by the Admin, i saw there was only option of sharing printer.
if it is possiable that printer remains avaliable to evrey computer on netwok without logging into the server please guide me how to do it.