Compiling Bootstrap

Hello,

I downloaded Bootstrap 4 Alpha and as far as I understand, I need to compile it. There are some .scss files in the scss folder and I think I need to compile all of these into one file, but I don't know how to do.

I tried a single file to test it and it works.

var elixir = require('laravel-elixir');

elixir(function(mix) {

    mix
        .sass([ // Process app stylesheets
            'app.scss'
        ], 'public/css/app.css');
});

NodeJS, npm and gulp are installed and when I run gulp from the command line, it compiles some stuff. How can I tell Laravel to compile everything in the resources/assets/bootstrap folder (including JS and SCSS files)? Do I need to include every .scss and .js file manually in the gulpfile.js or is there another way?