I've been playing around with backgrounds myself and have discovered a couple of tricks.  If you have the paper backdrops you can open one in your paint program and try using your BG image as a fill.  You can adjust the size of the BG image to fit the  panel.  Another way to do this is to open your backdrop panel in DAZ and then select it from your surfaces tab.  Browse for a background jpg you like and select it.  If it doesn't fit, fiddle with the horizontal and vertical settings until it does.  I've had great success with this method.  I hope you will, too!