I need to know how to get the calipers off to change the brakes on my 92 buick lesabre. Thank you

If you have never done disck brakes, you really shouldn't without some help and a service manual to let you see everything that needs to be done. The calipers themselves unbolt and simply slide off. But the piston has to be slide in the zero pressure position (completely contracted),that needs to be done with some care and then the brakes will need to be bled after installing the new pads and putting the calipers back on. Haynes or Chilton sell manuals that describe the process in great detail. Any auto parts store usually sell one or the other.