With the piston compressed, you should be able to easily slide the caliper assembly over the new pads. Once you have it on there, replace the bolts you removed and tighten them snugly. Press the brake pedal a few times to make sure you have solid brake pressure. The first pump or two will be soft as the piston finds its new starting point on the back of the pad.
Put your wheel back on, being sure to tighten all of the lug bolts. Now double-check your lug bolts just to be sure.
You're done! Feels good, right?