The camera has a variable shutter. That knob adjusts the shutter angle. From 150 degrees (Open) to 0 degrees (closed). It has nothing to do with the aperture.
If you want to do a fade in or fade out in camera (as opposed to in post) you just need to turn that knob with the camera running. From "Closed" to "Open" for a fade in. From "Open" to "Closed" for a fade out. It's in the manual (http://www.mondofoto...m814electronic/). There's a shutter table there too.
Personally, I leave it on open, and lock it there (that little slider thing is the lock). Since I edit on a computer anyways, I just do the fades there.