To add a Scene, select the Scenes icon on the left side navigation.

Click "Add new scene" button to create a new scene.

To edit a scene, select the existing scene.

For a new scene, you need to select a room, and the current state of the lights in the room will be displayed as basis for the scene. You can at any time for new or existing scene click "Refresh current state" to pull as scene values the currently playing modes.

Selecting "Edit light modes" gives you the detail of each entity (device or group) and you can define with more granularity the scene.

Different types of light modes are available. Custom ones, dynamic ones (with a speed), and simple ones.

Note that OFF is also an option for a scene.

Once your scene is finalized, click 'Save" to have it added to the list of Scenes for the room.