The concept and overall composition of this is very nice. But the too bright background jumbles everything together and overpowers the gumdrop trees. Distance (*even imaginary types) is often conveyed by a graying effect, as red and yellow tones are more short light waves. If you were to slightly desaturate that background with a gradient adjustment layer, and possibly increase the color saturation of the gumdrop trees just a bit to help them "pop" a bit more, your "candyscape" will have a much better visual presence. As is, if you squint your eyes slightly to blur the entire image, you will see that is a somewhat amorphous blob needing a more distinct focal point.

the source is www.wikimedia.com

Your link doesn't work, and there are obviously multiple sources. You need to post a link for every source used.
Author, this isn't the first time you've been warned about posting source links. Read http://www.pxleyes.com/blog/2009/06/how-and-where-to-find-legal-source-images/

5.11. Use of Search Engines to Find Source Images: If you find images with google or yahoo image search, it doesn't mean they're not copyright, always check the source site to see if the image can be used or not. Wallpaper images are usually copyrighted.
Please take time to read http://www.pxleyes.com/guidelines/photoshop/