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.