Documents unwillingly stored in iCloud
I have a MacBook Air that when I now try to save a document displays the message "out of space" below the icon. I am aware this is because my iCloud storage is full.
I do not want to use iCloud - I have purchased an external hard-drive and copied all my documents on to it.
The problem I now have is that, I do not actually know where my documents are saved to on my Mac! When I delete things off the iCloud, they also disappear from my desktop even though I thought I had copied them all from the iCloud to my desktop.
On finder, when I click 'Devices' and then 'My MacBook Air' / 'Macintosh HD' / 'Users' / 'Saffron' there does not appear to be a desktop? Is this where I need to save my documents?
How do I save my documents to my Mac and not the iCloud? and how do I then prevent this from happening again?!
MacBook Air 13", macOS 10.13