How do I set up my computer to upload ONLY 1 folder to OneDrive and save all other files to my computer?

I take notes using OneNote(ON) on my iPad&laptop. For changes to sync, Notebooks are uploaded to OneDrive(OD). My OD is full, so "freed space" from OD, by selecting which folders to upload (those with notebooks). My problem is: the files that I deselected are gone, but when I go back to OD settings, the "deselected" files are still option to select. When I go to folders, Gone. Can anyone help: 1.figure out where my files are? 2.help me set up my computer so that only my ON Notebooks sync to OD?
Answers

AJ

For 2, you have to select by folder what you want to synch, you do this by manage storage on your computer. But how do you use up 1TB of storage on OneDrive?