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.

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Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Donec odio. Quisque volutpat mattis eros nullam malesuada.
Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Donec odio. Quisque volutpat mattis eros nullam malesuada.