Instructions
Check to see if your SDHC card is compatible for use with your Wii at the Wii Brew website. If your SDHC card is compatible for a Wii, you need to format it before using so that the homebrew can be recognized and read from your SDHC card when using the Homebrew Channel on your Wii.
Format your SDHC card by going to "Start," "My Computer" and right-clicking on your SD card. Select "Format."
Select "QUICK" as the format type and format the SDHC card to FAT32. The FAT32 partition is read from the SDHC card when in the Wii. Click "OK" when ready to format the SDHC card.
Transfer your homebrew applications, emulators, operating systems and/or utilities for your Wii to your SDHC card in corresponding named folders. The homebrew applications will now be compatible to use and access from the Homebrew Channel on your Wii.