To change the background click on the label bar and in the layer window select the style tab.
Choose a source from the background top tab then upload an image or pick a background color.
To add a layer, click the green plus button in the left sidebar and select the type of layer.
Select any layer and you can edit its content and style properties in the layer window.
Your content goes here. Edit or remove this text inline or in the module Content settings. You can also style every aspect of this content in the module Design settings and even apply custom CSS to this text in the module Advanced settings.