Thermostat location and replacement?

If its some thing you are willing to do go for it
the way I would do it
ask for a helper to sit in the car

starting with engine cool open filler cap and top off coolant
start engine and let it idle for a few min then turn heat on check coolant level and add as needed
ask the helper to raise the RPM no more than 2000rpm
add coolant as needed
helper watching the coolant temp
don’t allow it to over heat
when engine reach temp and have heat and its full place cap back on
let it idle for few
shut engine off let it cool
and then check coolant and adjust
and if it still overheat on you then you have a different problem check if thermostat was installed correctly
good luck