The first Secret Treasure Map is located in the "Flute of the Growlin' Goblins". At the bottom of the pit behind the large totem pole is a little white object sticking out of the ground. You must ring the bell to make Bonelich appear. Play the music the correct way and he will give you the first secret treasure map.
Align the Wiimote vertically so it is parallel to the screen and pointed at the ceiling. When you need to "shake" for an individual note, sweep the Wiimote towards your body in a single motion. When the red squiggled lines appear, use a rapid back and forth motion towards your body then towards the screen.
The third Secret Treasure Map is located in "The Fountain Guardian". After you drain the pond you can find Bonelich at the bottom. You must ring the bell to make Bonelich appear. Play the music the correct way and he will give you the secret treasure map.