well, generally, you unbolt the caliper from on one side and loosen the other.
then swing the caliper off the disc, and you should be able to drop the pads out.
replace pads. (replace clips, shims, grease as necessary)
use some kind of flat object to get levarage on the pistons and push the pads apart.
swing the caliper back onto the disc, re-bolt, tighten.
how you actualy get the pads out might change, but the process is pretty much the same for any disc brake.