How do you change a thermostat for an 1988 Chevy Celebrity?

To change the thermostat on a 1988 Chevy Celebrity, 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 (ensuring proper orientation), reattach the housing and hose, and refill the cooling system with coolant. Finally, reconnect the battery and start the engine to check for leaks and ensure proper operation.