CREATING A SIMPLE EXPRESS APP

Use express-generator to create an app called whatever you want wherever you want it, but this is how to create my-app inside a Development folder in your home directory.

cd ~/Development
npx express-generator my-express-app
cd my-express-app
npm install
npm start

Open up localhost:3000 in your browser.

That's it.

MAKING CHANGES AND RESTARTING THE SERVER

TWEAKING THE EXPRESS APP BEFORE YOU GO FURTHER

To avoid having to restart your server, install nodemon with npm install nodemon (while inside the /my-app folder), then add a devstart script for using while you develop the app by adjusting the "scripts" section of your package.json:

"scripts": {
  "start": "node ./bin/www",
  "devstart": "nodemon ./bin/www"
},

Now restart your server