Now that we've gotten the CV joint apart, it's time to clean it up. Cleanup has a twofold purpose: to get the old grease off of the parts, and to facilitate inspection. You can't see cracks and pitting underneath a layer of grease.
A clean rag (several will probably be needed) is great for cleanup. As you wipe, look at the surfaces of the outer bell, the center star, the cage, and the balls themselves. You shouldn't see any pitting or any cracks. If anything is cracked or if pitting is severe, you should replace that part. Some types of CV joints have individual parts available for sale. Others can only be purchased as a complete CV joint.
Once you've gotten everything cleaned and inspected, it's time to either find some new parts (if the CV internals were damaged) or begin re-assembly.
First, the center star goes back inside the cage. Note which side of the cage was marked, and which side of the center star was marked. These two sides will need to face the same way after they're assembled.
Take the cage in one hand and the center star in the other. Rotate one of the star's ridges into one of the cage windows. You might have to try several rotations before the star will slip easily inside the cage. Again, don't force anything.
Once the center star is back inside the cage and both parts are facing the correct direction, it's time to get the assembled cage and star back inside the CV bell. That, however, is for tomorrow.