Enjoy my full website here. An all inclusive website on how to get started in Astrophotography:
https://depratnt.wixsite.com/astrophotography
This tutorial will take your through a very simple process called selective sharpening. You will be able to selective sharpen the areas of your astrophoto that you want sharpened while keeping the background and all other areas untouched. This will allow for sharper details and if done correctly, a three dimensional look to your imagess. Enjoy!