For installing the Homebrew Channel, we recommend using [ModMii](https://sourceforge.net/projects/modmii/). It's a good tool, and you can get a guide generated with instructions.<br>
[SetMiiUp](https://gbatemp.net/threads/setmiiup-from-stock-to-latest-softmod-in-less-then-5-10-minutes.459416/) is also a good tool to get you started.<br>
However, these tools do not give instructions on how to install RiiConnect24 or Wiimmfi, so use the guide here to install those if you want to (it's optional).
These instructions will assume you're using an SD card to mod your Wii with, but you can use a USB storage device in place of an SD card if you want (LetterBomb requires an SD card though).