Creating and understanding Scenes:

The Scene class is the root container for all objects to be drawn on the screen. A Scene has a specific amount of Layers, which themselves can contain a (fixed or dynamic) amount of Entities. There are subclasses, like the CameraScene/HUD/MenuScene that are drawing themselves to the same position of the Scene no matter where the camera is positioned to.
The scene is a subclass (extension) of the Entity class.

1. Creating new Scenes:

Creating scenes is really easy, its just matter of one line:

Scene newScene = new Scene();

Read this article, if you still do not know how to manage scenes (display/switch them)

2. Scene without background:

yourScene.setBackgroundEnabled(false);