You have to have caught a Chocobo in the Forest first. Then take out the Ziner, walk around, and press X (I think, or whatever button uses it) a bunch of times until the mother chocobo walks over to you and digs something up. The treasure is always a bunch of stones.

To find the treasure in the Forest of Solitude you have to tell ChocoBoy to move, because he is standing where it is.

When you have found every treasure in all of the Forests, then you can go to the final forest. To do this, ride the chocobo out of the forest by Trabia Garden. Then you have to go to the long penninsula to the east (look at your world map, you'll see it) and run along the shallow water until you reach a beach that has dark-green forests by it. Next, just go north until you see the final forest. You have to watch closely because it is kinda hidden. Once you get to the forest and watch the chocobos dance, talk to the chicobo in the middle and it'll give you the "Chocobo" card. But in your Card inventory it will be "Chicobo". I don't know why it does that.