How do you replace thermostat in 07 grand prix gxp?

To replace the thermostat in a 2007 Grand Prix GXP, first, ensure the engine is cool and disconnect the negative battery cable. Drain the coolant from the radiator, then remove the upper radiator hose connected to the thermostat housing. Unbolt the thermostat housing, replace the old thermostat with a new one, and reassemble everything by reversing the steps, ensuring all connections are tight and refilling the coolant. Finally, start the engine and check for leaks.