Astrophotography is a complex activity, you can not simply point a camera at the sky and take a photo. There are a wide range of technical challenges that must be solved. Learning the basics is just the first step in the process, there are a multitude of small issues that need to be addressed while photographing. Few are of any great difficulty, but there are a lot of them.
Astrophotography is learning to dispense with the plethora of small details, any of which can ruin the photo if not dealt with. Learning to photograph the stars takes time, practice and experiencing more than a few failures before the skills are mastered.
