Replace the brake Master

Here is a guide that will help with replacing the master cylinder:

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

You are going to have to bleed the system as well so here is a guide that will help with this:

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

Below is the process from the manual that will help as well. Please run through this info and let us know if you have other questions. Thanks