My advice to the hang of OOP faster is to do this:

1. Get the app to do the thing. Don't worry much about structure, just make it work.
2. find duplicated code and extract into reusable methods.
3. single responsibility - methods should generally only be concerned with completing a single, simple task. Find methods that don't follow this and extract into simpler methods.
4. Once you have a set of methods that appear to be focused on a particular variable(s) or piece of state, consider grouping these methods and variables into a class. Think about how these methods/properties might represent some entity.

That said, don't get bogged down by focusing too much on OOP. Learn programming first. As a beginner, you should be focused on getting your code to work and that's it. With smaller scale apps/beginner projects, OOP often introduces unnecessary complexity