I assume you use CameraFTP VSS (Virtual Security System) software. If not please visit www.cameraftp.com and download VSS.
To turn off your screen, you can set this up from your computer's Power settings. The exact steps are dependent on your operating system. Overall, it should be quite easy.
You can set the computer to turn off screen after x minutes. Please make sure that the computer will not be turned off, or enter sleep / hibernation mode.