This is quite easy as long as you have to proper tool. Get the car in the air and support it with jack stands. Remove your wheel. Remove the bolts that hold the caliper in place. Remove the pad from the caliper. With you special tool (basically a metal block with protruding nubs. any parts store should have them) turn the metal caliper foot counter clockwise until its recessed all the way. Install the new pads. Once the car is back on the ground make sure to pump the brakes because the new pads will be away from the rotor. If you just drive away the car will be hard to stop the first couple times.
Answer
That response is too basic. First. Get a book with pictures that tells you how to change the brakes. Then turn off the air suspension and then lift the car and support with jacks under the axle. After removing the wheel, have someone turn the other wheel while you observe the pads and rotor for signs of warping. ABS brakes-Remove the emergency brake cable from the housing braket-(not easy). You will need a hex tool to remove the caliper bolts. This can be a real pain in the butt if they are frozen. Use plenty of lube spay and vice grips. Remove the anti rattle retaining clip that holds the brake pads in place at the bottom. Remove the pads and reset the caliper (if its good, otherwise you will need to bleed the brakes requiring a full replacement of only DOT 3 fluid(not Dot 4). When resetting the caliper, some fluid may need to be removed from the brake reservoir. Its always a good thing to clean out the reservoir with rag and fresh fluid. Remember brake fluid attracks moisture easily so do not leave the reservoir open for long periods. Use a bungi cord to secure the caliper up and away from the rotor (be carefully not to over stress the brake line). Remove the rotor and gently clean up the ABS ring with a wire brush and treat with light lube. If re-using the rotor us light sand paper to remove the glaze and wash it clean. With the rotor in place, put on the new pads and Use special caliper bolt lube on the entire bolt and tighten. Don't forget to reattach the anti rattle retaining clip and the emergency brake cable (lube it too). With the brakes back together (reservoir full) and wheel off turn the key on to energize the system. Pay attention to reservoir level and pump the brakes a few times, add any additional fluid. Turn the opposite wheel to make sure the wheel turns freely. If everything oK then apply Never Seize to the wheel lugs and put the wheel back on and tighten the lug nuts in a star pattern.
Don't know what you want to know about the brakes
Front brakes are done the usual way but the back pistons have to be screwed into the calibers not pushed in.
you need to take off the master cylinder and the accumulator and replace it with a master cylinder from a non antilock vehicle like a thunderbird or cougar from about 1985 to 1988.
Yes, they have the ABS brakes.
where is the starter relay located on a 1990 Lincoln mark 7
Front or rear?
Not true, they have power brakes.
May be the proportioning valve by the master cylinder
And what about it do you need one ? selling one ? Fixing one?
Not unless you try to change the whole front end of the car.
behind kick panel on the passenger side next to the door
No, but you can install a spring suspension.