These are the images that I used to create my piece. the one from the mountains is a photo I took in Colorado and I wanted to do something to it to make it look more interesting. 
I started by removing the blue parts of the sky and leaving just the clouds, and then I added the starry sky behind it. 
After that I turned the opacity of the clouds down to make it all blend together better, and I added a streak of color in the sky. 
After cleaning everything up I added a moon and this is my final piece. 
Starry Sky
Published:

Starry Sky

Published: