The ISO images you will mostly be dealing with are rips of commercial Wii games.
Here you can find ways to use them.
► Burning an ISO onto a disc -- How to burn a backup disc.
► Dumping a game -- How to use your Wii to dump commercial Wii games.
► Extra Setup for USB loading -- What to do with your USB Drive before you can use it.
♦ FAT/NTFS for Windows -- How to use a FAT or NTFS drive for USB loading on Windows.
♦ WBFS for Windows -- How to use a WBFS drive for USB loading on Windows. (Not recommended)
♦ WBFS for Mac OS-X -- How to use a WBFS drive for USB loading on Mac OS-X. (Not recommended)
► WBFS Managers -- Add ISO's to your Hard Drive.
♦ Wii Backup Manager -- A Windows program that supports FAT and WBFS drives, as well as ISO, CISO, and WBFS images.