How do you replace slack adjusters?

They are the adjusters on the rear drum brakes. There is usually a oval shaped hole on the rear of the backing plate where you can use a special adjuster screw or a large screwdriver to turn the adjustment star. You want to adjust them for a fair amount of drag without the wheel and tire mounted on it. 'After adjusting that way and after you remount the tires, , back the car up , in a straight line a few times to set them automatically and to the correct tension.