Installation

Use 7zip or WinRar to extract the files.
Pick between 1 of the 3 choices 
No Galaxy
No Aurora
No Galaxy or Aurora

Move the Data folder to your Skyrim folder.
You can find the Skyrim folder here: Programfiles(x86)\Steam\steamapps\common\skyrim\data

Data\textures\sky\skyrimauroralut.dds
Data\textures\sky\skyrimaurorastreak01.dds
Data\textures\sky\skyrimaurorastreak02.dds
Data\textures\sky\skyrimauroraswirl01.dds
Data\textures\sky\skyrimgalaxy.dds