These instructions will assume you're using an SD card to mod your Wii with, but you can use a USB storage device instead. However, the exploit LetterBomb requires a SD card due to how the Wii Message Board works.
Some alternatives to this guide are [ModMii (if you have Windows)](https://sourceforge.net/projects/modmii/) or [SetMiiUp](https://gbatemp.net/threads/setmiiup-from-stock-to-latest-softmod-in-less-then-5-10-minutes.459416/).
Both of these allow you to get started via a guide, however they do not install other services by default, which this guide shows.