Shuyn

Hello.
I'm in the last year of a programation course, but now i have to do a project in delphi.
My project is to control a room with some computers (see what they doing and be able to turn in/off the screen).
About the part of be able to watch what they doing in the Computer is done, i used some VNC code on my Delphi project and its working properly, but about the Screen control i cant find anything to let me control screen (turn it off or on remotely by a Administrative computer on the room).
My teacher said there have some porgrams and code to do that, but he wont tell me how to get it
Can someone help me about how can i control screen by a Computer program and dont let them turn in without Administrative autorization please?
Thank you very much for read and help

Sorry for my bad english, but i'm Portuguese