iOS 8 is here and the only thing left for you to do is update your iPhone or iPad. While updating to iOS 8 over-the-air is faster and more convenient, if it's not showing up for you, we can walk you through how to manually update via your computer with iTunes.
How to update your iPhone or iPad to iOS 8 through iTunes
Before beginning, be aware that you'll need to be running iOS 7 or newer in order to update over-the-air. And you'll also need to make sure your device is supported. These are the iPhone and iPad models capable of running iOS 8:
iPhone 4s and newer
iPad 2 and newer
iPod touch 5th generation
Back up your iPhone or iPad with either iCloud or via iTunes.
Make sure you're on the latest version of iTunes. Go to About and then Check for Updates or visit iTunes.com.
Launch iTunes on your Mac or PC.
Plug in your iPhone, iPad, or iPod touch if it isn't already.
Click on iPhone, iPad, or iPod in the top right navigation.
Click on the Check for Update button under the Summary tab — alternately, if you'd like to restore your device clean and wipe everything you'd click the Restore option instead.
An update should be recognized, click on Download and Install in the popup menu and agree to any terms or conditions.
That's it. Simply leave your iPhone, iPad, or iPod touch plugged in and let iTunes do its thing. Once your device reboots, you should be running iOS 8. Just be sure you don't disconnect until iTunes is done.