Navigate to the path that contains your theme's js files. It should look similar to this root\content\themes\\assets\js, where is the name of your current Ghost theme. For reference, I use a slightly modified Casper theme. Place your ghosthunter.min.js file in that path.
Now we need to reference the ghosthunter.min.js file in the default.hbs file, located at the root of your theme. Open the file and add the following line of code after ghost_foot: 041b061a72