SpringBoot On logging dcos, please explain how to log in application code and where to put logging configuration

Documentation enhancement request.

Page in question: https://docs.spring.io/spring-boot/reference/features/logging.html

As a beginner, this is the first page that comes up when I search spring boot logging. It does not say how to log in my application code, or give any clear indication of where the numerous configuration XML snippets should go.

This page gives a little more clarity, but still leaves me very far from accomplishing basic tasks: https://docs.spring.io/spring-boot/how-to/logging.html

Please help a newbie who has never heard of the three logging frameworks named, and just wants to customize the log format a bit. Thanks!