From here you can download skins for your PG Calculator. After you download ZIP file with skin you should unzip it to separate folder in "Skins" directory located in PG Calculator install path. For example if you installed PG Calculator in "C:\Program Files\PG Calculator" and next download "Metallic" skin you should create "Metallic" folder in "C:\Program Files\PG Calculator\Skins" path. Just click on image of skin you want to download.