I've tested it again. Ok I see why I didn't get it. When you click on something, you have no feedback, so I didn't understand I was taking pictures or anything else.
Also I didn't get how the encourage/discourage system works. I still have a lot of captions available, some encouraging other not.
Except that, I love the game, it's cute, and even with no feedback when clicking, it's really fun to see how the world evolves with your actions.