Stonewrought UI seeks to restyle the default Classic interface in a Dwarven influenced style.
Extract the Stonewrought_UI zip file and paste the contents of the “Interface” folder directly into your Interface folder (Not the Addons folder).
There are some alternate textures that you can swap if you prefer (see shots). To do so, delete only the files that you intend to swap from the Interface folder, then replace them by pasting the alternate files into the Interface folder.
Example: delete the Minimap folder from the interface folder and replace it with the Minimap folder inside the Stonewrought_Alternate_Versions/Alternate Minimap_01 folder.