Fishing Guild Leader Santiago:
Since you agreed, I'll take it that you accepted the experience. I'll explain in simple terms, you always need to learn the theory first.
In order to fish, you need to find a fishing dock. Once you arrive at the right spot, you'll see the button on the right side of your screen that alerts you that you can fish. If you see that button, it means you've found a right spot.
Fishing docks are at the Iris Lake, Narsell Lake, Giran Harbor. near the Plains of the Lizardmen, the banks near the Town of Gludio, the Neutral Zone, Heine, Fellmere Lake, and the bridge near the Town of Giran. Understand so far?
"I Understand."