If you don’t have a Heroku application yet, take a look at this how-to.
DATABASE_URL with the credentials of your new created database (1) in the “Config Vars” section (2). Here you can add more if necessary (3).
Your new database has no data yet, so you will need to import your local data to this new one.
To do that, you first need to create a dump of your local database.
That’s it! Your local database is now available as your production database on Heroku. 🎉