If you don't use a pre-made store bought one, you'll have to buy an enema bag. Fill it with water and use the rectal side of the hose and insert it. Rise the bag up and let the water flow in until you feel full. Try to retain the water as long as possible. Its been about 15 years since I've done a home enema, so maybe somethings changed, but that how I remember it. It not hard at all, but you won't want to do it very often as your colon will get used to it and stop contracted the way it should.
The store bought fleet enemas have the directions on the back.