Once you have conquered the HelloWorld example, you should start looking at Box2D's samples application. The samples application is a testing framework and demo environment. Here are some of the features:

Camera with pan and zoom.
Mouse dragging of dynamic bodies.
GUI for selecting samples, parameter tuning, and debug drawing options.
Pause and single step simulation.
Multithreading and performance data.
Replay viewer for debugging recordings from your game.

The samples application has many examples of Box2D usage in the test cases and the framework itself. I encourage you to explore and tinker with the samples as you learn Box2D.

Note: The samples application is written using GLFW and imgui. The samples app is not part of the Box2D library. The Box2D library is agnostic about rendering. As shown by the HelloWorld example, you don't need a renderer to use Box2D.