Girl in a Mountain Hole - using the dimensional aspect.

1/. First the original image.

 

2/. The Hole in the Mountain Image.

3/. The original girl image. (In this case the option image/rotation/flip horizontally was used).

Using the Quick Selection Tool, select the girl, but not the background.

4/. Copy/Paste the selection image onto the mountain.

You will need the Edit/Free Transform tool, to place the image.

5/. Copy/paste again, reducing the image size. (in the second layer the Opacity was also dropped to 24%.

6/. Copy/paste again, reducing the image size. (in the second layer the Opacity was also dropped to 22%.

7/. Copy/paste again, reducing the image size. (in the second layer the Opacity was also dropped to 25%.