[Mortarius]

I did a quick search but couldn't really find what I was looking for, but I recently started to try out PhotoShop and I love it. I wanted to make some custom art for my UI such as re-skinning the cast bar, action bars, minimap, etc. Problem is I have no idea where to even start to put something I create in PhotoShop into the game. If someone could give me an idea or point me in the direction of some ways I can read up and learn to do this it would be greatly appreciated!

P.S. Long time user of WoWInterface and have always loved this community. ^^