The great thing about containers is that you don't have to understand the full scope of how they work in order to use them.

You can start with learning how to use docker-compose to get a set of applications running, and once you understand that (which is relatively easy) then go a layer deeper and learn how to customize a container, then how to build your own container from the ground up and/or containerize an application that doesn't ship its own images.

But you don't need to understand that stuff to make full use of them, just like you don't need to understand how your distribution builds an rpm or deb package. You can stop whenever your curiosity runs out.