my finished product (i'm not sure how to add a shadow for him....)
I picked this picture to use
and this picture of my dog (I took a picture of him last winter inthe snow...and apparently caught him peeing, lol)
I use gimp, I opened the dog picture, went to layer>transparency and added an alpha channel and erased the background then saved it as a PNG file (supports trasnparency. then used the flip tool to make him face the other way
then opened the picture of the hydrant
went to file, open as layers and opened my dogs picture on top of the hydrant picture, then used the scale, rotate and move tools to move him where I wanted.
went to dialogue to see the layers, unselected the hyddrant and adjusted the brightness and contrast of my dog to make it look more "real"
then merged the layer, selected a pale yellow color to paint, and selected "soft light"
(I just learned how to open as layers today too!)