Welcome to GBtemp.net!
If you need questions, ask me. I'm like a general homebrew games guru.
How are you modding your son's Wii? Modchips? The Homebrew Channel?
Homebrew: Home-made games for various systems.
Modchips: Hardware designed to edit the already existing hardware on a motherboard.
The Homebrew Channel: A homebrew Wii Channel that can be installed in many ways: Allows for booting of homebrew in the form of .dols and .elfs.
.dol/.elf: Files used by various Wii homebrew launchers to play homebrew.
Homebrew Launchers: These launch Homebrew in various ways such as The Twillight Hack, The Homebrew Channel, or BannerBomb.
The Twilight Hack: An exploit in Nintendo's Legend of Zelda: Twilight Princess can be used only for System Menu 3.X and under. It invloves downloading a save for your region, copying it to the Wii, and then starting up the second save file. The save works by having Link's name changed to a long code, which If the person in front of you when you start tries to pronounce it or you exit the level which will read the code. It will then load the boot.dol or boot.elf file that is in the root of your front Wii SD Card.
BannerBomb: A Wii "Channel" that when you try to copy it to the Wii it will instead load a loader for .dols and .elfs.