Background: 
Express is a Node.js web application framework. It utilizes HTTP utility methods and middleware, which makes creating APIs much simpler than with Rails, for example. 

Node is a JavaScript runtime environment that is mostly used for server-side programming.

Knowing JavaScript is not a pre-requisite for this tutorial, although it will be helpful. Nevertheless, it will become crucial as you advance past this tutorial. 
Follow these links to familiarize yourself with the technologies mentioned in this tutorial. 
Express
Node
JavaScript

01. Open a new project folder in your favorite code editor. Next, open up the terminal and run “npm init”.
02. Add Express to your list of dependencies by running “npm install express”
03. Create a new file in your project directory called “app.js” or “server.js”. In it, create a basic server.

Now, you can run node server.js in your terminal. You should see it output “Running on port 3000” or whatever string you defined in your .listen. Next, go to localhost:3000 in your browser. There, you should see “Welcome to my API”, or whatever string you defined in your .send.