1. Extract Bf-109 K-4Black4Wotowski.rar to \\Eagle Dynamics\DCS World\Bazar\Liveries\Bf-109K-4
2. Choose a description.lua from one of the two folders - depending on wether you want the skin with or without swastika (default.lua is withouth swastika)
3. In the mission editor choose "Schwarze 4 Wotowski" as skin in the payload tab


credits to JST and Maler for providing excellent templates!