Once you have downloaded and installed the app, you will be prompted to either log in with your Twitch account or create one. This app has the same functionality, with some cosmetic changes added in.
You can start by downloading the Twitch App here - this used to be called the Curse Client, prior to Twitch acquiring Curse, a name many of you are likely more familiar with. This is by far the simplest of the three options and the most safe of them. There are a few different methods depending on the addon you are downloading, so we're going to go over each of them with a step-by-step guide.
Addons open up a whole new world of possibilities for your user interface (UI) in WoW - the question is, how can you start downloading them and getting them running in-game?