Quick.need the settings to put my camera on for lightning?

I have a nikon d3100 and it's heat lightning outside right now and it's dark so i need to know what settings to use real quick. I have tried what i read on google but the picture comes out dark.

Added (1). Okay so the only way i can get to bulb is under (M) mode and i have it on bulb but the aperature is at f5.6 and i don't know how to change that.

You need to use the bulb setting which keeps the shutter open. You need a tripod and need to keep the front of the glass covered by a dark plastic or black folder until such time that the lightning is captured.

Use a tripod. Try ISO 100, bulb shutter speed and an aperture of about 7.1. If it is too bright use a higher aperture. If it's not bright enough use a lower aperture.
Hold your shutter open until you catch a burst. Could be as much as 30 seconds or more. Check exposure and adjust if needed.

Come back and let us see what you got!

Also, set the lens to manual focus and infinity