how to use a Mac laptop and data projector?

Hi,
I need to know where on a Mac laptop you turn on the “video monitoring” ? I am going to a meeting soon where I am using a new Sony data projector and the Mac which I have not seen nor used before.
Do I need to use any function keys etc.? Some new projectors suppose to have now a auto scanning function to detect a signal. I had trouble once before where i could not get from the laptop monitor to the projector.
Any advice would be much appreciated.