As far as I know, it's the bleeding to mae sure there are o air bubbles is the important bit,
Thermostat is at the end of the bottom rad hose (on passenger side)
3 bolts to remove thecasing and the thermostat will pop out, Put the new one in (the right way around)
Put it back togetherand then fill up at both the rad and expansion tank,
I think put the rad cap back then you run her at tick over and top up as required, when the thermostat opens the water level will rise suddenly, expansion cap back on quicky,
Check levels the followig morning,
All this is just my opinion, I am a carpenter, If you are at all concerned, lave it upto one of the traders!
Dan