The outer threaded part has 2 different diameter threads on it. One end will fit the sprocket and gear, the other end will fit the clutch.
Be very careful when threading it in. Due to the fine threads used, it is all too easy to cross thread it. I will go so far as to use a toothbrush on the tool's threads and the threads on the item to be pulled to insure that there is no debris to interfere with the threads.
The following steps are assuming that you all ready have remove the retaining nut and lock washer(s) from the item to be pulled, as well as cleaned the puller threads from said item.
Step 1: Remove the center screw and clean and oil the threads both on the center screw and the larger threaded part. All the threads inside and out.
Step 2: Determine which end of the larger threaded part of the tool properly fits the item to be pulled.
Step 3: Carefully thread the tool into the item to be pulled, taking care to not cross thread it. Note: you may need to use slip joint pliers or similar pliers to hold the gear or sprocket from turning while the tool is being threaded in. If you are working on the clutch or pinion gear, you can wedge a penny in the teeth where the 2 gears meet to lock them in place.
Step 4: Snug tighten the tool into the item to be pulled. There are hex flats on the outside of it to enable you to do this. Use a properly sized wrench or Crescent wrench. Do not use pliers on the tool. Only snug it up, do NOT tighten it like it was a head bolt!
Step 5: Thread the center screw into the larger part of the tool. Use 2 wrenches. One to hold the larger part of the tool and one to tighten the center screw.
The item to be pulled should come free with little trouble. It if seems like it does not want to come free, tap the puller's center screw with a small metal hammer while the puller is tightened up. Notice I said tap, not hit a home run on it. Sometimes you will need to tap a little harder or give it 30+ taps. Each tap set up vibration between the parts to be separated and this usually will do the trick.