very simple if you follow the procedure in the workshop manual

undo and do up the bolts in the correct sequence

easier to remove the head with inlet and exhaist manifold in place. don't forget to remove the turbo oil drain - easiest is to disconnect it at the short hose where the outlet pipe joins to the sump

make sure that your head and block are in good condition and flat

make sure you get all oil and water out of the head bolt holes

cut the heads off 2 of the old head bolts, cut a slot in the top with a hacksaw in case you need to use a screwdriver to get them out, and thread them in only a couple of turns to use as a guide for the new gasket and to put the head back down square

get a cometic cam cover gasket as they are re-usable and sseal better in the first place.

use new rubber seals around the cams and plenty of sealant around the cam bearings