Shaders Mod 1.8.1 Here

: Download and install the Minecraft Forge version compatible with 1.8.

The mod itself only provides the "engine"; you need a "pack" for the actual visuals. How To Install Minecraft Shaders For 1.8 (Step by Step) Shaders Mod 1.8.1

: Run Minecraft 1.8.1 at least once from your launcher to ensure all base files are present. : Download and install the Minecraft Forge version