Looks straight forward enough.
Remove cover, lift out thermostat, fit new one replace cover using new sealing ring (#24) and probably new sealing rings (#15 and #16) on the coolant pipe
Remove bolts 18 and 19. You will also need to slacken off a bolt, not shown, that goes through the other hole in part 17, so as to be able to turn it round.
Then remove bolt 32.
The hole assembly comes off, with tube part no 25 still fixed to the thermostat housing.