How to install shaders.
This tutorial will serve as the written guide on how to install shaders. It will cover everything you need to know.
To start, you will need some things. For starters, if you are on 1.8+ you will need Optifine. I will only be covering these versions for the length of this tutorial. You can find the latest version of Optifine here: Optifine Downloads, simply download the latest version for the Minecraft version you wish to run.
After you download Optifine, you are ready to start. This section will cover how to install just Optifine. The next will cover how to install it with forge. Download and launch the version of Minecraft you wish to use. Close it, and double click on OptiFine_X.XX.X_HD_U_XX.jar and click install. This installation will create a new profile on your Minecraft launcher, just select that in the bottom left and click play.
forge and optifine installation
For forge the process is different. I am assuming you already have forge installed so I will skip those steps if you do not simply google how to install it there are plenty of tutorials. Double click the OptiFine_X.XX.X_HD_U_XX.jar file and click extract (Unlike the standalone version). This application will prompt you with a window where you can select a path, navigate to your mods folder forge created and click okay. Doing this will drop Optifine into your mods folder, only launch the game under the profile your forge is in! That's it you're done.
If you go into your video settings, you will see a Shaders Option, if it says you need to turn off fast render that is located under the performance tab. In the shaders tab, you will see open shader packs folder. If you click that it will open an explorer window, simply drag in the shader pack you wish, they're usually .zip files so just drop that in and select it in game. You will note an area called shader options in the shaders tab, there you can select options for your shader if the developer enables them.
if you need extra guidance, I recommend this video from past life pro. How To Install Shaders For 1.11