how do animals exactly work?
i get them with the green cards putting them in my warehouse.
And then? All i do is to try to get four different and that's it?
You're trying to get sets of different animals. You can have multiple sets. From the rulebook (p. 14):
Example: Megan owns 3 sheep, 2 cattle and 1 chicken.
She gets 3 victory points for this (2 for sheep + cattle
+ chicken, 1 for sheep + cattle; nothing for the single