Hi I'm trying to connect a new programmable thermostat the old 1 has white black green and red wires, the new one has a spot for red black green and orange.What do I do I'm pretty sure orange is for central air which I have so I don't know why it's not there or what to do with the black.

Thanks.

Did you make notice of where the wires were when you disconnected the old stat?
Check the terminal board on your furnace. Where are the wires connected to on there?