Instructions
Updating Wii Firmware to Version 4.0
Highlight the "Wii" icon on the lower left corner of the main menu. Press "A" with your Wii Remote to select the option. Select "Wii Settings" from the subsequent menu.
Read the number on the top right of the screen. If the number is below 4.0, proceed with the update. If it is 4.0 or above your Wii is already updated and can read 4GB SD cards.
Scroll to the right twice to cycle to the third list of options. Highlight "Wii System Update" and press "A." Click "Yes" to confirm the update. Click "I Accept" to begin the download and installation process.
Wait for the blue bar to fill completely. After it has filled, the console will install the update and restart.
Downloading Rock Band 2 Content
Insert a 4GB SD card into the slot located on the front of the Wii console, adjacent to the disc slot. Start "Rock Band 2."
Choose "Yes" when prompted by the Wii to "Enable SD Card Mode." This will only appear if you have an SD card in the console when you begin "Rock Band 2."
Scroll down to "Music Store" and press "A." Cycle through the content on the music store using the directional pad of your Wii Remote. Press "-" to sort the songs alphabetically, year of release or by difficulty.
Highlight a song you wish to download and press "A." Scroll down to "Purchase" and press "A." Select "Yes" to begin the download.
Press "A" to continue after the song downloads. It will automatically be transferred onto your SD card and be available for play in the game.