Hello!
Just add the plugin file to your RPG Makers plugins folder, than enable it in the Plugin Manager inside the engine.
For details on how to use it please read through the help section! =]
If you mean instructions on how to load and activate the plugin in the engine, try taking a look at the official forum, as there are a great variety of tutorials that may help you: https://forums.rpgmakerweb.com/index.php
But if you mean instructions on how to use the plugin after installing it, you can read the documentation either in the Plugin Manager interface after loading the plugin, or by opening the file in a text editor and reading the help section (which is the same text that is displayed in the Plugin Manager interface).