Apple Application Support is not available as a stand-alone application instead is bundled with every Apple software you download and install. The easiest way to get the application is to install any Apple software (iTunes in your case) and using the default options the software provides perform a fresh installation. These Apple applications run based on the additional software they provide meaning that when you install Quicktime or iTunes for example you have the possibility to uncheck what you don't need but later you will realize that what you unckeched is very important for the good functionality of the future operations regarding file transfer, burning, etc.
