Following are instructions for the 2.7. I'm presuming you have the V6
since the four has two belts.
You'll either need a 3/8 drive ratchet or a 17mm open end wrench,
depending on your tensionser type. Release the tension using the
appropriate tool and slide the belt off one of the pulleys. You'll need
to remove the two 12mm bolts holding the tensioner in place and remove the
tensioner. Remove the belt and put the new one in place, reinstall the
tensioner, and then, using the same tool as above, move the tensioner and
install the belt.