For the background I went with some sunset on some clouds. Sadly I suck at clouds, but You get the picture.
As for the sand dunes. My google referencing told me that you need lots of dark areas where the light isn't hitting the sand directly. I think this is because of the high brightness of the sand that makes the dynamic contrast of cameras pick up even the bright shadow sides of the dunes as really dark. Dynamic contrast OP.
Also lots of round shapes that end in spikes.