I have never done a case study before and showed how I make a photo manipulation from step one. So I’m showing you what goes into making one for anyone who doesn’t use photoshop.
First I started out with a picture of the eiffel tower ( I got all these images from sxc.hu, so I can use all of them legally)

now because there are all those people and dead grass, I decided to add some more “lush” grass so I inserted the grass from this picture:

and added some bushes to cover the surrounding areas of the eiffel tower:

I then wanted to make it into a dark, stormy scene so then I added a lightning sky:

I adjusted the colors a bit to make everything match, added a filter to give it a “vintage” look and added some stars with a photoshop brush. My final image is this:

Hope you enjoyed :)