This creates three new directories called: To get started, download the World of Warcraft Interface AddOn Kit and use that application to extract both User Interface Data & User Interface Art.
If you find an Add-on suitable for your needs from one of these sites, you will find using them much easier than attempting to create a new add-on yourself. These sites have customized interfaces and add-ons for almost every conceivable need, so it is extremely unlikely that you will need to create an add-on from scratch yourself.
With that said, there are a number of websites devoted to user interface customization (add-ons) available, such as WowInterface and Curse. If you break it, you get to keep both pieces. No official support exists for modifying the WoW interface. Customizing the interface is a very technical endeavor, (although Lua is an extremely simplistic language, comparitively speaking) and you should not attempt it unless you have a good working knowledge of XML and Lua. This document is a short introduction into modifying these files to customize your interface. The interface of World of Warcraft is built from XML files, which describe the look and layout, and lua files, which contain scripting functionality. World of Warcraft user interface customization guide (for 1.12.1 vanilla WoW) 1 World of Warcraft user interface customization guide (for 1.12.1 vanilla WoW).