Settings for Holga Lens for Nikon?

I've just received my Holga Lens HL-N for Nikon DSLR Lomo but I still can't seem to figure out the settings for it. The pictures are too dark:-( Can someone help me please?

You have to know how to work your camera in manual to use any of those lenses. You have to know how to balance the exposure triangle. I could give you settings and they may or may not work. It's all about metering the light and setting the camera up according to that measurement and the scene you are working in.
Wait… Your meter probably doesn't work thru that lens either. You need to have a hand held meter and that will actually tell you the settings you need! Http://www.adorama.com/SKL358.html