Instructions
Open the flap below the disc tray on the Wii console and insert an SD card with the label facing toward the disc tray.
Turn on the console and go to the Wii menu.
Click on the "Wii Settings" icon in the bottom left corner and then select "Data Management."
Select the data type that you want to back up, either "Wii Channels" or "Save Data."
Click on the channels or data files you want to back up and select "Yes" when asked "Copy to SD Card?"