1. Extract Bf-109 K4 Gelbe 14.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 "Gelbe 14" as skin in the payload tab


credits to JST and Maler for providing excellent templates!