A Sequence can consist of 3 different Layer types:
To add a music file click the green plus icon above the layers and select "Audio". Then double-click on the created audio layer and select an audio file from the file dialog.
You can fine tune details of the audio block by clicking on it. This will show it's parameters in the inspector panel. Additionally, you can move the block to change it's start time. You can also use the nudges at the beginning and end of the block to crop the music clip.
Add a music file.
You can add Light Blocks to a Block Layer in the following ways:
The Light Blocks will display a visual representation of the output.
Adding a Noise Light Block with Drag and Drop.
Adding a Noise Light Block with Drag and Drop.
You can add a smooth fade-in or fade-out to each light block. Click the Light Block to show its parameters in the Inspector. Then enable the "Fade out" parameter and change the value.
Add a Fade out.