Download the framework from Github.Download SCSS
Become aquainted with the grid system and how it functions. Read the documentation.
Read through the documentation of the components.
Set the variables to your liking in the _variables file. Things like the color scheme, amount of grid columns and spacing are yours to freely alter.
This step is optional. If you're familiar with Gulp.js, install the dependencies outline in the gulpfile and use Gulp to compile your SCSS.
Link to the CSS
Once you've had a play with the variables, link to your CSS file from your HTML file.
<link href="/css/surface_styles.css"/ rel="stylesheet">
That's it! Go forth and build the website of your dreams!