good start but It would have been nice if the background was drawn by you. The composition is ok, but it does look like she is floating. This is because of the tree, for this to make sense with the way the tree is sitting you would have to have her feet below the bottom of the page, character design is a bit crazy but I like that, it's different and she is cute. I would also say that because you haven't painted the background and it is a bit dull and dark, it just doesn't go with her at all. The pattern across her top is a bit too straight, it looks like a stamp, you need to put curves and bends in it to make it look like it is flowing and clothes-like.
Digital art is hard and it takes a bit of time to get used to, it is also hard to not just say "well its digital I can just copy and paste" any one can do that but you want to stand out and make your stuff your own. Eventually you will be able to understand everything more. What program did you use for this?