Alrighty!
So I've spent about the last three weeks on this.
I've looked at hundreds of tutorials, and dozens of images, and finally came up with this. It isn't exactly what I wanted, but I'm still learning.
It was supposed to be a bit darker, more rainy and the unicorn was supposed to be the shining light in the picture.
OH WELL!
I'm pleased with the horn, and how I managed to make the background seem like it was the original picture.

Comments? Critiques?


Credits:
Rocks from : [link]
Horse from : [link]
Background behind castle from : [link]
Cloud and Rain brushes from :

Castle and Rocks+Waves are my personal photos. I'll post the links to them once I upload them on deviant art.
Moon and unicorn's horn are done on adobe, with credit to me.