sync or backup documents to icloud

Hi,

I want to keep my working documents on the desktop so I don't have to be online to access them, but have an auto-sync/backup to iCloud which does not necessarily backup the entire hard disk including all the software as I already run Time Machine onto a stand-alone hard drive. Is this possible and if so, how do I do it? I tried but seem to have moved my entire desktop and documents onto the cloud which is absolutely not what I wanted. However, storage on the machine still shows a hefty amount there, so presumably it hasn't been wiped?

I'm using a MacBook Pro, 2012, 13 in, with OS10.13.6.

Help, please?

Thanks

MelissafromColchester