Instructions for backing up to iTunes or iCloud. Only one method of backup can be used.
Back up to iTunes
Step 1: Connect your device to your computer via USB sync cable.
Step 2: Depending on your previous setup, this may launch iTunes and start the sync process, which includes making a backup. However, if your device isn’t set to auto-sync, continue on to Step 3.
Step 3: If you see a Trust This Computer message, go ahead and agree to it. In iTunes, click the iPhone/iPad icon (near the upper-left corner) to bring up the Summary screen for your device. Then, in the Backups section, click the Back Up Now button. Depending on how long it’s been since your last backup, this might take 30 seconds or a decent chunk of time.
You may want to consider enabling encryption for this backup, which will carry over iOS “keychain” info (passwords for email accounts, Wi-Fi networks and various apps and web sites) as well as any Health or HomeKit data you may have – if these are features that you use. Just tick the box next to Encrypt iPhone backup before hitting step 3. Be sure to note the password you’re using for the encrypted backup.
Back up to iCloud
Step 1: Make sure your iPhone is connected to a Wi-Fi network.
Step 2: Tap the Settings icon, then tap iCloud.
Step 3: Turn on the items you want to backup to iCloud. Tap Backup, then toggle iCloud Backup on (if it isn’t already). Finally, tap Back Up Now. Depending on how much time has passed since your last backup, this may happen quickly, or it may take hours. Plan ahead.
Step 4: Verify that the backup finished successfully by tapping Settings > iCloud > Storage > Manage Storage, then selecting your iPhone. You should see details of the backup, including time and size.