How do I mount my rear bumper on my 98 jeep grand cherokee

How do I mount my rear bumper on my 98 jeep grand cherokee I have a 98 jeep grand cherokee,when I bought the jeep, the rear bumper was not there .I have the trim not the metal bumper itself.I purchased a new metal stock metal bumper and the plastic goes over that,but how do I mount th bumper to the jeep