Kewl! I like how you used the Ashenvale trees combined with the world tree, purty damn sweet for a first terrain, what are you going to have around the tree? It's kinda flat n' boring there. :>
By the way what is those shiny things on the tree?
its very nice for a first attempt, more tile variation, raise and lower, then just continue more of the same doodad use, and youll have a very nice woodland setting