Not too fond of the glow on your character. and the font would look better if it were in the tree line, just above the dandelions. but this bg isn't going to work unless vectored. the quickest way to vector it would be to vector a few of the dandelions in the front then place them all next to each other on a new file (make sure the bg in the new file isn't any colors). flatten then duplicate, and place the duplicate next to the other. keep doing this until you have a full row, save the file here, saving it here is important. then continue the duplicating process to make the back, so shrink it as you go. place the row (still in the new file) where it would be in the picture, then make two duplicates of the row, and place them so they ends meet in the middle, you do this so you don't get lines down the bg, and give it a more random growth look. you can just flatten and duplicate the image, while placing the duplicates randomly, and doing things like flipping it horizontally to make the top half of the field. after you have the top half save the file under a different name than the regular sized row, open the regular sized row and place the image in the current file. make a set for it. shrink it until the dandelions are just a little bigger than the others, and duplicate it enough times to make a full row. duplicate the set, and follow the same procedure as before, but only make a few rows. then start increasing the size of the sets as you go, until you get to the front. save it, when your satisfied, then flatten it, and place it in the bg of the wall.

a similar process can be used for the trees. make your own sky, this one doesn't look good at all. and put some cloud brushes on it.

of course, if you want to spend less time than vectoring it, just use the same process with brushes. this way you could use other flowers if you wanted. the wall will still have the same feel and design, but it will match the anime character. i know it's a lot of work, but the end result will be amazing, if done right.

good luck!