Oh, that is simple. First, you need to know wich version you want to use (the icon class name is different on other versions). Then embed the right version on your html code (there are several way to do that) you can search for awesome font install and read the instruction.
For now i prefer you to try my favorite version by adding this code inside your head section of your code: <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
this is version 4.7, then just find the class name of the icon you want, and insert this code in where you want to use in your code: <i class="fa fa-car"></i> ("fa fa-car" is the class name of the icon).