It helps to be in a place very dark with no city lights. But the basic setup uses a high iso, greater than 800. Next leave the shuttler open 10-30 secs. Also a bright aperture setting, less then f4.
Both images used a 30sec exposure/800 iso/f3.5 / 18mm lens
On those night pictures, I took advantage of light from a street lamp to have the trees bright. Using light from campfires, tents or even the moon adds to the picture.
Hope that answers your question.