Meow! It’s pretty much a waiting game. If the cat comes often enough, it will eventually give you a ‘treasure’. What happens when they give you a treasure is that the screen will suddenly go black (don’t panic!), a cat will walk across the screen and stop at the center of the screen:
Tap on the cat and the treasure will appear!
You can still see the treasure at the cat’s profile or at ‘treasure’ under the main menu.
If you click on the individual treasure, you’ll see the description, which is the same on the cat’s profile.