Video is not clear at all

I am a window user, Don’t know about vi and all. How can I deploy my flask app to Heroku and I have doubt too about how things work when we use gunicorn. Its server runs on and when we deploy our flask application to heroku, why it is showing Hello!, since it is implemented in route ‘/’ but webhook() function is defined in route f’/{TOKEN}’ which is returning Ok. The video is not clear at all.