Complete and check the following two factors before continuing:
1. Backup the Device
It’s always best to be safe and start out by backing up your device using iCloud or iTunes before doing anything.
2. Verify You Have Enough Space
If you’re device is running low on space, this can cause issues with installing the update. Verify you have enough space and if not, you can delete content from your device manually or see here: https://support.apple.com/en-us/HT204204#space
Once you’re finished with the previous steps, you’re free to move on to ‘Updating Wirelessly.’ If your device doesn’t show the Update, move on further down the page to ‘Update Manually.’
Updating Wirelessly
First begin by making sure your device is plugged into a power source and connected to a reliable WiFi Connection.
Now, on the device go to Settings > General > Software Update.
Tap ‘Download and Install’
Note: If you’re asked “temporarily remove apps because iOS needs more space for the update” tap ‘Continue’. Later, iOS will reinstall apps that were removed.
(If you’re not comfortable with this, select ‘Cancel’ and see above on how to make space on the device.)
You’ll have the choice to “Install Now or Later”. If you choose later, you’ll have the choice to “Install Tonight” or “Remind Me Later”. Just be sure to have your device connected to the WiFi and power source (plugged in) when scheduled.
If you’re device has a pin code, you will be asked for this. Enter your pin code and you’re all set.
Additional Note: whether you use iTunes or update wirelessly, you’ll have the same amount of free space on your device after you update.
Updating Manually
If the update isn’t showing up for you, you can push this update manually using iTunes. It’s best to be sure your iTunes is up to date as well. You can verify by downloading the latest version of iTunes here: https://support.apple.com/en-us/HT201352
- Start by connecting your device to the computer and opening iTunes.
- Select your Device in the panel on the left-hand side.
- In the same area on the left hand side, select ‘Summary’.
- On the right hand side, select ‘Check for Update’.
- Once finished, select ‘Download and Update’.
- If you’re device has a pin code, you will be asked for this. Enter your pin code and you’re set!
Don’t know your passcode? See here: https://support.apple.com/en-us/HT204306