Instructions
Without Cheats
Insert the Guitar Hero disc into the Wii and start the game like normal. Choose the "Career" path and press the Green button.
Scroll to your band name (or if you have not started the game yet, scroll to "New Band"). Press the Green button.
Scroll to the simplest level you feel comfortable with. For a surefire way to unlock the songs, scroll to the "Easy" level. Press the Green button.
Scroll to the "Play Show" option and press the Green button. Press the button again to start the show.
Play through all the songs in order, in the Career mode. If you complete them successfully, they will be unlocked to play at any time.
Unlocking Cheats
Insert the game into the Wii System and let it load. Scroll down to "Options" on the main screen and press the Green button.
Scroll down to the "Cheats" menu and press the Green button.
Scroll down to "Enter Cheat" and press the Green button. A representation of the fret bar will appear.
Press these keys in this order: Yellow & Orange, Red & Blue, Red & Orange, Green & Blue, Red & Yellow, Yellow & Orange, Red & Yellow, Red & Blue, Green & Yellow, Green & Yellow, Yellow & Blue, Yellow & Blue, Yellow & Orange, Yellow & Orange, Yellow & Blue, Yellow, Red, Red & Yellow, Red, Yellow, Orange. Press the "+" button to enter the code. All songs should now be unlocked.