Flask Python Web application framework tutorial (1 of 3)
Flask Web Development with Python Tutorials ( 7 videos)
https://www.youtube.com/playlist?list=PL6gx4Cwl9DGDi9F_slcQK7knjtO8TUvUs
Tutorial and specially on submit button
https://blog.miguelgrinberg.com/post/the-flask-mega-tutorial-part-iii-web-forms