how to deploy heroku app

$ git add .
$ git commit -m "Added a Procfile."
$ heroku login
Enter your Heroku credentials.
...
$ heroku create <app-name>
Creating arcane-lowlands-8408... done, stack is cedar
// now create procfile
//
//node app.js
// 
$ git push heroku master
-----> Node.js app detected
...
-----> Launching... done
       http://arcane-lowlands-8408.herokuapp.com deployed to Heroku

$ git push heroku master

I assume you know how to use git.
I also assume you've ran the heroku create command for the app.

First commit the app if you haven't, then run this command:
git push heroku master

If there's an error, then try to fix it.

After that access the website by running this command:
heroku open

And run this command if you encounter an error with the website:
heroku logs --tail