How do you change the headlight in a 93 Toyota Tercel?

If you are referring to just the bulb, if you find the wires running to the headlight, it should be as simple as a quarter to half turn counter-clockwise and the harness, with bulb, should slide out of the housing. Then you take the bulb out of the harness, put a new bulb in, slide it back into the housing, and a quarter to half turn clockwise locks it back in place.