There are 2 large bolts that hold the caliper in place. remove these bolts and the caliper should slide up. Watch for the shims, they will fall out. Take a small c Clamp and clamp the edge of the piston and tighten it slowly and the piston should slowly collapse back into the housing. This will allow you enough room to install the new pads, shims, etc and when you get the caliper back in place, be sure to tighten your bolts, check your fluid level then, bleed your brakes of any air. This is done by pumping the brake pedal, holding it down then, opening the bleeder screw slowly so the air escapes. Be sure to place a piece of hose over the bleeder so the brake fluid does not run down onto the brake pads that you have just installed.