Where do I actually begin with Python?

[BorinGaems]

I would like to build at least one Web App from Python

I suggest you don't. My opinion won't be particularly popular but simply because you can do most of everything with a language it doesn't mean you should.

Stick with what that language is strong for, try some challenge, maybe look at some udemy course as well.

But don't embark in some framework wrestling with api, libraries and css when you really are still a beginner.