the pulley in your pic (stationary pulley) is easy to change, if you have to change the tensioner pulley, its a little tricky. You have to line up the tensioner bolt housing and the pulley bolt when putting it back together.
these are the bolts that you need to get to in the diagram
the pic of the broken bolt (dont do lol) is the tension bolt and the square part is the housing the pulley bolt goes into. its behind the metal frame the pulley is on
you can see it if you climb under your jeep behind the front driver side tire.