Instructions
Power on the console and open the Nintendo Shop Channel. Click the "Start Shopping" button to open the main shop menu.
Select "Add Wii Points" and follow the onscreen prompts to either redeem a Wii Points card (which you can purchase from a local store) or input your credit card information and address to purchase a selected amount from the store. If you have any problems with this step, consult the Nintendo website under "Resources." One hundred points represents one dollar.
Confirm that the Wii points have been added to your account by checking the balance at the bottom of the main Wii Shop menu.
Return to the Wii home menu and start the Guitar Hero III game disc.
Open the "Downloads" menu, and browse the in-game download shop to find the songs or track packs that you want to add to your game. You can purchase individual songs for 200 points, and track packs contain three songs for 550 points.