To deploy on Heroku, you need two additional files in your folder. A requirements.txt that lists all the python libraries Heroku will need and a Procfile which contains the code that runs your app.py.

To see what python libraries you have on your computer, go to a terminal and run pip freeze. To put these libraries in a files, you can run pip freeze >> requirements.txt. However, you also need to make sure to have gunicorn library in the requirements as well.

The Procfile will stay mostly stay the same for any project as long as you consistently name your server file app.py.