1) Press B, cast your line.
2) After about 15 seconds or so the bobber will start to sink below the surface.
3) The bobber is colorred from bottom to top something like: Red, Yellow, Green, Yellow, Red. When the Yellow (2nd from top) goes under water, put the remote directly above your shoulder (I faced the Wiimote either straight up or directly away from the screen, I don't recall). When this happens, it should say "Fish On"
4) DO NOT MOVE The Wiimote, it's not necessary (For this fishing pole) to do anything but hold the Wiimote up high.
5) I had to catch a 2nd fish for the cat plot.