How to backup Mac to iCloud

Here is a resource that may help.

• How to back up your Mac - Official Apple Support

Apple does not offer an iCloud backup for Macs, only for mobile devices like iPhones or iPads. You can back up your Mac with Time Machine, as pointed out by Sean_W (How to back up your Mac - Official Apple Support) or use third-party cloning software to clone your Mac to a backup drive.

If you want an additional off-site copy of your documents and data, you can sync your Mac with iCloud Drive to store the Documents folder and Desktop in iCloud Drive, or use iCloud Photos to keep your photos in iCloud. This will not be a backup, as the files in iCloud will be the versions you are working with, but will give you the added security, that you can recover the documents from iCloud if the Mac is damages, lost, or stolen. But you will still need a local backup to be able to recover older versions of the documents and data, or accidentally deleted items.