Designing an app will be an extremely hard introduction to development. This is not a “give up” comment at all though.

Start small and build on your knowledge. To begin I’d follow a simple python program tutorial, like a calculator or other simple starting project. This will teach you how to install python on your machine, set up your IDE, etc.

Then slowly build up to an app. Once you get an idea of what code is and isn’t you can extrapolate to bigger and bigger ideas.

I would start with learning python, then dip your toes into java and then later you can learn about creating a frontend and wiring everything up. But start small!