Run it
Copy the script and paste it into your executor.
local sky = Instance.new("Sky")
sky.Name = "CustomSky"
sky.SkyboxBk = "http://www.roblox.com/asset/?id=15088936211"
sky.SkyboxDn = "http://www.roblox.com/asset/?id=15088936211"
sky.SkyboxFt = "http://www.roblox.com/asset/?id=15088936211"
sky.SkyboxLf = "http://www.roblox.com/asset/?id=15088936211"
sky.SkyboxRt = "http://www.roblox.com/asset/?id=15088936211"
sky.SkyboxUp = "http://www.roblox.com/asset/?id=15088936211"
sky.Parent = game.LightingMario.exe skybox

Universal