How to Extract the Background
1 I’m going to take the sky/background out of this picture so we can put in a night sky. Open your image and copy the whole image then close that window. Go to File >> New and click ok, Now paste your picture there.
2 Now zoon in to about 500%, Take the Eraser Tool with the third smallest brush in the top row. Now go around the outside of what you would like to keep in that picture. See how I did mine, your not going to get it perfect.
3 Once you got the outside done take the biggest brush in the top row and finish the rest of your picture. Hold the Crtl key and click on that layer it should select the picture. Now go to Select >> Inverse then hit the delete key on your keyboard to delete what’s left.
4 Now you can put your own background or what even in you want. I used dark blue and black for the night sky and put a glow on it.