In creating my collage I chose a collection of photos that represented summer and sun and fun. I used two sky photos, a photo of a guy somersaulting on the grass and, one of a girl basking in the sunshine. I also selected a sunflower and a photo of a hot air balloon.
To merge them into a collage, I primarily used the Magic Wand tool, the Smudge tool and the Clone Stamp tool. I placed each photo on a separate layer and then decided which areas of each photo I wanted to show.
I blended the sky images using the Smudge tool. I removed the sky portion of the background in the photo of the guy using the Magic Wand tool. I also used the Magic Wand tool to remove the background from the photo of the girl and the sunflower. I used the Quick Mask Mode tool to clean up the some of the rough edges left by the Magic Wand tool selections. I then reduced the layer with the hot air balloon to 50% opacity to give it the illusion of it being farther away from the other images. Finally, I used the Clone Stamp tool to adjust the sky and grass line.