Tap your name at the top of the left-hand menu
Tap 'iCloud Backup'
Make sure iCloud Backup is toggled to on (green)
Tap 'Backup Now'
You can see the date and time of the last successful backup on this screen. If you do not have a recent backup choose 'Back Up Now'. The device is now backing up. If you have never backed up your device this could take a while. Please be patient.
No date with just a time means the backup was today.