hi thank you for the question hope this helps
looking at the engine follow the upper radiator hose toward the engine were it meats the engine is the thermostat housing
remove the thermostat housing and you will see the thermostat.
to replace the thermostat follow these steps
Drain some coolant into a clean container until the coolant level is below the thermostat housing.
Remove the upper radiator hose connection from the thermostat housing.
Loosen the housing bolts and remove the housing.
Remove the gasket and scrape it carefully from the surface of the housing and the mounting surface on the engine. If the gasket remains on either of the surfaces, there will probably Be a coolant leak after reassembly. Some engines use a rubber O-ring to seal a thermostat housing.
Installing is this
Install the gasket.
Reinstall the thermostat housing. Refill the system and run the engine or pressure test to check for leaks.
When the engine has reached operating temperature make sure the thermostat opens.
You should be able to see coolant circulating within the radiator.
Another way of checking thermostat operation is to feel the top of the radiator hose or use a thermometer or multimeter with a temperature probe to confirm that the coolant is warming up.
If the engine is overheating, but the top hose is still cool to the touch, the thermostat is stuck closed and must be replaced.
good luck
If I was helpful please click the accept button bonuses are appreciated If I haven't answered your question completely just respond for more help
Thanks
David