Move the file to your VirtualDJ skins folder (usually Documents/VirtualDJ/Skins ).
Save the skin file (usually a .zip file) to your computer. Do not unzip it . Virtual Dj Mix Lab 3.1 Skin Download
The safest way to get this skin is through the official Virtual DJ Skins forum , where you can find the updated version optimized for newer software engines. Move the file to your VirtualDJ skins folder