Have you downloaded the service manual? It is explained there. Follow the link in the Sticky thread in the front section of this subforum (assuming that old link still works.)
So you have a belt diagram, good, but for those that don't, first thing, before you do anything, make a drawing of how the belt runs over all the pulleys to use as a reference.
Have look at this old thread on the subject ( post #2 specifically),
http://www.ausjeepoffroad.com/forum/...belt+tensioner
It explains the process and direction of rotation to release the tensioner.