Go to node.js and install the latest version. It will walk you through the installation process.
Once you've done that, just clone this repo and open it up in your favorite code editor.
Before you can run this app, you will need to install all the needed dependencies. NPM makes this very easy. All you have to do is open your terminal, make sure you are in the project directory, and run npm install.
To run the app, make sure you still have your terminal open and run npm run start. This will start the app, and then you can go to localhost:3000 and see your app running with a "Hello World!" message!