After you’ve backed up your iPhone or iPad, you’ll have a copy of your information to use in case your device is ever replaced, lost or damaged. You can back up your device manually, or turn on iCloud Backup to automatically keep your device backed up.
Tap Back Up Now. Stay connected to your Wi-Fi network until the process has finished. Under Back Up Now, the date and time of your last backup will be displayed. If you receive an alert stating that you don’t have enough iCloud storage space to complete the backup, follow the onscreen steps to buy more iCloud storage.
Automatically back up with iCloud Backup
Go to Settings > [your name] > iCloud > iCloud Backup and make sure Back Up This [Device] is turned on.