How do you change the headlight on a 1990 Ford F150 pickup?

are u talking about the bulb or the whole headlight assembly if its just the bulb there should be a black ring on the back of the head that unscrews and then the bulb just pulls out. if your talking about the whole head light assembly. the first thing u have to do is remove the piece of black plastic that covers the head lights and the grill. 2nd remove the grill from the front of the truck. then depending on what side of the truck your replacing the headlight u have to remove the battery or the windshield washer bucket. once this is done there are four bolts that hold the headlight assembly onto the front of the truck 2 are on the front of the truck underneath where the grill was. and then there are 2 more on the inside where the fender meets the radiator support. remove these four bolts and the headlight assembly will come out then just unplug the head light and the turning signal and the headlight is completely out