Hardware Modifications
Hardware modifications allow the console to bypass certain built-in software checks, enabling the console to play custom software programs. This is a moderately difficult Wii mod to perform; you'll need to purchase a mod chip from an online retailer and follow the installation instructions carefully. Installation generally involves dismantling the Wii case and soldering the mod chip onto a specific section of the Wii console, though the exact location where to solder the chip depends on the type of chip you purchase. When purchasing a Wii mod chip, be sure to purchase it from a reputable dealer.
Software Modifications
Software Wii mods involve taking advantage of loopholes in the Wii's native code to load custom software that enables you to use homebrew applications and games. This type of modding is not as involved as the hardware mod, because you don't have to open up your Wii, but it does require that you know how to download and configure a considerable amount of software. The general approach is to download custom firmware onto an SD memory card with your computer, and then load that firmware onto your Wii through its SD slot. Be warned that this process, if done incorrectly, can "brick" your Wii, leaving it in a state that is unusable, and you will have to send the console back to Nintendo for repair. Unfortunately, if this happens, because you loaded custom firmware onto the console, Nintendo may decide that the console is no longer eligible for repairs.