The first step, obviously, is to take the pictures with the camera. In order to get those very faint targets, I have to use very long exposures -- 4-10 minutes per image! Since the camera is electronic, each individual image has "noise" that I don't want in the final image. The goal is to get the highest signal-to-noise ratio possible and then use Photoshop to manipulate the image to pull out the faint stuff. This is done by taking many images and "stacking" them together to average out the noise.
This image represents a stacked image. Notice that you can see the stars and a little color, but not much else. This is similar to what you would see if you looked through the telescope with your eye. Also notice that the sky isn't black! That's due to skyglow and light pollution. We may not see it with our eyes, but the camera can see it, especially during long exposures.