Need to know full low voltage wiring information to thermostat

Usually the Red wire provides 24v and connects to the R termenal-
Next the Green wire is to the indoor blower motor and connects to G terminal-
Next the Yellow wire is to the outdoor unit to call for cooling and will engage power to the contactor solenoid to pass 240v power to compressor and power to Start/Run capacitor and fan! It will connect to the Y terminal-
Next is the White wire an it calls for Hea and is connected to the W terminal-
If you have an Orange wire it is for the reversing valve of a heat pump system.
Remember the red feeds 24v to each of these colored wires to complete a connection and pass power to the device being called into action.
BLue or Black wire will be ground if the thermostat needs power instead of batteries.

Red wire is the only hot 24v wire going to the thermostat period! And it comes from the Transformer!