The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From LikeBit Creations:
Background Designer is wonderful application for designing your own Lock Screens by mixing pictures or wallpapers from your phone with a variety of skins and frames. The screens even look very pleasant if you assign them to your contacts images. Now create some outstanding Lock Screens and Contact Images and amaze your friends. Features, - A vast variety of skins and frames to choose from. - We have precisely chosen each and every frame and skins to create gorgeous backgrounds. - Support for 640x960 Retina display. - Very simple and easy to use interface. - Option to preview your work before you save. - No complex and unwanted features added, so you just end up with simple and sober backgrounds.