You can use images as overlays to create effects in your image. Which image do you think has an overlay added?
Plenary
What are the uses of a Overlay?
Reveal
Overlays in digital photo editing are used to define photos and photo textures (fog, leaves, feather, petals, snow, rain, sun flares, etc.), which are added to the photograph as an extra layer in JPEG or PNG format.
Is your image becoming too busy? The rule of thirds may help.