Hi goslings,
To find files on your Mac that you have worked on/created since a certain time, you must use the Finder. That is the whole point of the Finder. Do not feel intimidated with the Finder. You cannot hurt anything unless you are looking for trouble.
- Go to the Finder.
- In the menu bar, select "Go" > "Computer".
- Click the Search field and input a term.
- Click the "+".
- (You may have to click "Other"), but now, you can access filters like "Created date" and "Last opened date". You can then explore to narrow your search.
To check iCloud for a file, go to iCloud in the Finder, and verify the file is there.
Hope this helps.
Cheers,
Jack