In that case, a pop-up window announcing the upgrade appears when you launch i Tunes.
If you see that window and want to upgrade, just follow the onscreen instructions and you'll be running the i Tunes in no time.
See the System Requirements on the i Tunes download page.
If your computer is using Personal Hotspot on the i OS device that you’re updating, connect your computer to a different Wi-Fi or Ethernet network before you update.
If you need more space for a wireless update, you can update using i Tunes or delete content manually from your device.
Whether you use i Tunes or update wirelessly, you'll have the same amount of free space on your device after you update.
Here you can find music, podcasts, and video, plus anything you purchase is immediately available from any device where you sign into i Tunes with your Apple account. With a subscription, you have access to over 30 million songs in the Apple music library.
i Tunes is a digital media player, written by Apple Computer, for playing and organizing digital music and video files.