OK I have an old house 1975 with the mercury switch thermostat and a humidifer adjustment next to it. When I pull each unit away from the wall they both have only 2 wires attached to them.
Thermostat: Black & White wire
Humidifier: Black & White wire

I purchased a Honeywell RTH7600 7-day programmer.

Question is:
Where do I wire the Thermostat wires to?
And can I wire the humidifer wires into also? Or have to keep it separate.