A lot of images with the same idea it seems.. but as I finished this one already, gonna submit it anyways - took a lot of work.
I cleaned the tree picture and removed the girl from the sunset image. Made several pairs of wings with slight adjustment with rotation/perspective tools. Made an invert for white wings. Made the black wings a bit transparent with masking.
Made a new foot/leg and pants for the flying boy with pattern tool and coloured the pants with gradient map tool.
Used duplicate layers to alter sunset image colours and enchanced them by hand (more red, etc..)
Finally added a bit unrealistic but fun shadow/halo wing effect for the silhouette man.
* update **
Added a shadow for the bushes also, as Langstrum suggested. (5 years and 2922 days ago)