How do you reinstall a cylinder head on a 2.6liter?

depending on make/model, and engine type

i will asume its a v6 with 8 studs

make sure the gasket surface is clean and straight, on the block and the head,

place the gasket on the block , place the head on the studs,

put the washers on the suds, then tighten the nuts by hand,

get a torque wrench

tighten the middle 4 up evenly in a X pattern verry gently

then do the outer ones in a large X pattern

come back to the middle and do it again only this time tighten it to about 25 NM

then the others again, then go back to the middle and do them up at 35 NM

when you done them al at 35 then go around all the studs and check if they are still on 35 NM, now put the cams and stuff back in (assuming you did not take the valves out, or have placed them back) check valve timing before putting the valve cover and gasket back on.