Originals:
plus this:
intermediate step of this:
and finally you get this:
I wish I could give a good tutorial on this but it was quite some time ago. If I do recall correctly I removed my water dragon from the original picture using the magic lasso, and then I cut out the Nazgul from the LOTR shot and cloned and blended in a sky in its place. I then resized and inserted my water dragon into the picture after playing with his color via filters for a while to dull it down and make it blend.