Saving captured images from webcam with different default names

Question

Hello, i have an embedded circuit am designing (Home security Burglar alarm),it has webcam connected to it then to my Pc serialport,in event of burglar breaking into my home (by tripping the sensors) the device sends letter like " c "  to the Pc serialport which signals my C# application to activates for  my webcam (30secs to 2minutes) to take capture images of the burglar  and save it on my harddrive with different default names at different intervals this happens once my sensors are tripped on my hardware.
 Any clue or lines of code will be appreciated.