How do I run my js code in my terminal?

I have started learning the Full Stack Engineer and I am going through INTRODUCTION TO NODE.JS (
My question is, as I am learning how to run node.js with in CodeAcademy lessons and at the same time using my own terminal, I do not know how to run my js code in my terminal like I do in Code Academy.
I open my terminal and type “node” to navigate to node in the terminal, but how do run a js script once you are in node.js?
In CodeAcademy, you write your javascript code and then in the terminal click run, but how do I do that in my own terminal?
I hope this makes sense.

Thank you,
Mark Morse