Step #75 in the Total Overhaul list
If you are using Graphic Herbalism - MWSE and OpenMW Edition and have its patch for this mod, then all you need are the textures. Otherwise:
OpenMW 0.46.0 or newer required. Set
apply lighting to environment maps = true in the
[Shaders] section of your
settings.cfg file to fix shiny meshes, see this page about "shiny meshes", and this page about the settings file for more information.