Creating Theme Skins
The process of adding skins is very similar to creating custom WordPress themes. You need a style.css and a screenshot.png (optional).
Create a new folder in the theme's skin folder at theme > skins.
Create a new style.css in the skin folder. Then in the style.css, add the follow code at the top:
/* Skin Name: My Custom Skin */
Create a screenshot.png in the skin folder (optional). The skin should now be available within the framework under the Skins tab.
To remove a skin, simply delete the folder.