do you want transfer just to your computer or to a other device?
if you want transfer to your computer you must connect the device to your computer and right click the device in itunes in the side bar. than you can choose transfer purchases.
if you want to transfer to a other device, you must transfer the apps to your computer. than you must connect the other device and synch the app's, but you should entered the same appple id in the device settings.
and if the other device is linked to a other mediathek all contents will be erased on the other device and replaced with the new one