It's easy just un screw it and either clamp the brake hose or hold it up, plug a cap in, anything to stop the fluid pissing out. Then once you've sprayed the caliper screw the hose back in, tighten it up. Then undo the bleed nipple, apply a little pressure at the brake peddal, this will help push the fluid through the caliper and force the air out. Then once your happy its just fluid in the caliper tighten the bleed nipple. Next pump the brake peddel and it should go to a normal hard peddal and thats it, job done.
P.s don't forget to top up the fluid level after if needed.