10000 posts and you've never had your car in bits, come on son! Joking.
See the hose which comes out of the radiator at the top? A really short one which goes to the engine? Well you need to remove this pipe from the engine end. Then youl be faced with 3 10mm bolts in a triangle shape. also remove the thin pipe which goes to the header tank. When the 3 bolts are removed and the pipe the thermostat will come off, along with water.
When you get it off, just pull the old thermostat out of the housing an place in the bin. Get the new one, put the seal onto the big end (seal should be split all round so you can attach it. Place in the housing, screw on and reattach header pipe and rad pipe