How did Drag and drop questions work?

Hi, I'm new to opigno and I've problems to understand the "Drag and drop question". The "Drag and drop question with lines" works fine but I don't know how "Drag and drop question" work. I can upload multiple images which are shown, but how do I define the background image and the right position of the answer pictures? There is no video or describtion in the user guide. A describtion within the question editor is also missing. Why isn't there an opigno site where I can learn how opigno works? Or some kind of Wiki? The documentation must be improofed. At the moment I spend a lot of time with try and error. Best regards Kal