in N mode the shutter speed is abt 1/100 so yes your photos will be dark if u do get light.. one way i suse flash another way is u can set the setting to Bulb mode, that will aloow u to open the shutter for as long as u like so that it can get light, however if u have shakey hands than your photos will be blur, so either get a flash, or use a tripod . Tripod + shutter release cable will be the best option.
hope tt helped u