I am replacing a worn out Honeywell T8411R (non-programmable) Thermostat with a new Honeywell RTH7400/7500 7-day programmable thermostat ( Unit is a Trane Heatpump with Emergency/auxiliary heat. Of course I am having troubled

Can you help? I matched up all wire by Letter to new but I have an Orange, White and Black wires that aI am not sure where hey go...