How to change a thermostat on a 1999 alero?

flushed coolant . still overheating, while standing still mostly.... car is cooler on the highway.How to change a thermostat on a 1999 alero?
Dude

RTB that means read the book. Get a manual and read it. Also high quality tools (husky or craftsman) are a must. If you want to learn about cars find a shop that will let you, even sweep the floor and get a job in the industry. Always RTB if you don't know!!!How to change a thermostat on a 1999 alero?
The symptom you describe sounds like your cooling fan is inoperative. You just said it yourself, OVERHEATING WHILE STANDING STILL= no air flow through radiator. During vehicle cruising at highway speeds, there is sufficient airflow circulating through the radiator, which would not require the cooling fan to operate. One way to check this is to turn on the AC, and see if the cooling fan comes on. If not, either the cooling fan motor itself, or wiring to the cooling fan is the cause. Another way to verify cooling fan operation is to disconnect the ECT sensor with the vehicle running, the fan should come on at HIGH speed. If not, the ECT or its associated wiring could be the cause. Hope this helps. Good luck.