Renaming icons in iPhone, iPad or iPod touch is not possible, at least that’s what Apple has set on the original settings. If you insist on renaming the icons you need to have a jailbroken idevice. In order to be able to do that, you need to download Icon Renamer from Bigboss repository via Cydia application.
Don’t worry if you don’t find any new icon after the installation is completed because there is no really new icon for this small yet useful tweak. To rename an icon, tap and hold an icon until it is in the “arranging @ deleting” mode.