How to Shoot the Night Sky
First of all, there should be no ambient light (car lights, streetlight, etc. otherwise you will not get a clear picture, if it comes out at all. Set the ISO to 200-400. If yours is not a digital camera but a film one, just make use of a 200-400 ISO film. Choose the Daylight setting. Set the autofocus switch to the M position (to turn it off). The focus ring should be turned clockwise to the infinity symbol. Take a tripod, screw the camera into place and ensure a steady location of the tripod on the ground where you intend to shoot. Point the camera at the sky and connect the cable release to the camera. The recommended exposure time is 10-30 seconds.
As you will have to constantly change this setting during the session, it is better to do it using the buttons on the camera. In case your camera allows keeping the shutter open until you press the release button again, use this option instead. As soon as you are ready with these preparations, take the picture by pressing the button on the release cable. You will hear two snaps. At first, when you press the button and then when the exposure time is over. Experiment with different exposure times, the white balance and the ISO settings to take several pictures of the same piece of the sky to choose from.