Connect your iPhone to Wi-Fi
Open Settings
Tap your name
Tap iCloud
Tap iCloud Backup
Turn on iCloud Backup
Tap Back Up Now
Keep the iPhone connected to Wi-Fi until the backup finishes
To back up to a computer, connect the iPhone to a Mac or PC
On Mac with Finder, select your iPhone and click Back Up Now
On Windows or older Mac with iTunes, select your iPhone and click Back Up Now
Wait until the backup is complete
Check the backup date and time to confirm it finished successfully