The background in this piece was made using photomanipulation of a drainage canal I found in my own neighborhood. Here is the original photo:

To make the picture easier to edit, I put it in monochrome (pure black and white):

I then used a series of other photos to add onto the background:

As I did with the original photo, I put these pictures into monochrome and began to snip and transform pieces of them into the canal photo. Here is the result:

I exported the finalized background as a monochrome picture. This way when I reimported it into Clip Studio Paint, I would be able to select all the white in the picture and erase it, allowing me to color the image. I then put a transparency lock on the black parts, and that allowed me to color the black areas and the erased white areas separately. The girl was then added in post with a tone filter over the whole of the picture to give it a dreamy look.