It work on the same principle as a corkscrew for wine. You have the handle and then three different size slicer/corers for your pineapple.
Cut the top off the pineapple and chose the size slicer/corer you need. Attach the handle.
Then line up the bottom hole of the slicer/corer over the core and press down hard so the slicer goes right into the pineapple.
Once it's in securely, all you have to is start turning it. Hold it firmly in one hand and push down and turn.
You may get some juice bubbling up while you're turning, just tip the pineapple over and dump it into the bowl you're going to put the cut pineapple into. You don't want to lose that juice!
Turn it until you get to the bottom of the pineapple.
Now comes the tricky part. Turn the pineapple sideways and while holding it still, firmly grasp the handle of the slicer/corer and start pulling it out of the pineapple. There is suction at work here, so it's not as simple as just pulling it right out. It takes a little effort and at times, the handle will come off. Just put it back and on resume. With a little finesse, you'll be able to pull the whole pineapple right out of it's skin.
Take off the handle, flip it over and you have perfect slices of pineapple.
It then slides right off the corer part and you can either make slices (they are already sliced but all attached to each other) or chunk it, or whatever else you want to do with it! It's the greatest gadget ever!