Vintage MacBook Pro Backup

iCloud is not a backup. iCloud is a file syncing service so that multiple devices can access the same data. Plus with all the new security changes it may not be possible for a 2009 Mac to even access some iCloud features (depending on the OS that is installed).

If you want to backup the data on your Mac, then use Time Machine:

Back up your Mac with Time Machine - Apple Support

Even if you are using iCloud you should still be using Time Machine (or some other backup software or method) to have a backup copy of any important data so you have more than one copy of the important data.