How to connect audio/speaker cable with 4 conductors.?

Please excuse my ignorance, this is my first time to setup a house sound system. We recently bought a house with multiple in-wall/ceiling speakers and volume controls for each pair. To start with, I purchased a 6 zones switch selector and a receiver. The audio cable has 4 wires (red, black, green and white) and it all terminate in central location in the basement. I am confused and I don't know which wire to connect to the switch selector.