There are many different ways to build components using Metal.js. You can use the built-in integrations with Soy or JSX templates, or even build your own template abstraction on top of Metal.js and use it instead. You can build the ES6 code using Babel, Traceur or any other transpiler. You can test using Karma, Jasmine or any other test framework, and can use any directory structure for your project. To sum it up, you can customize everything to your own needs. The world is your oyster.
This guide will focus on a quick and easy way to get started with Metal.js. But if you are excited to try it out as soon as possible you can just play around with this JSFiddle.