As the titles indicates, I would like to search a file in a particular folder, and its subfolders, through Spotlight. Is it possible to do that in Spotlight? If so, how can that be done?
Short answer: No, you can not.
Spotlight is designed to be the "central search hub" of your Mac. So whenever you type in something, it will search everything (except "blacklisted" folders and file types that you can set within System Preferences as well as any data from all other user accounts and connected servers unless your account has permission to view them) on your Mac internal storage as well as any additional connected media storage devices.
If you want to search into a specific folder and its subfolders, you will need to go to the actual folder in Finder first. In this example, the selected folder will be "Treehouse"
Then, click on the search bar (typically on the top-right corner of the window) and type in whatever you need to search for. In this example, the term will be "iTunes".
Finally, you will see a gray bar below the Finder toolbar. Select the folder name within the gray bar (if it hasn't been selected already) and it will limit the search to just the files and folders within the said folder.
From anywhere in the Finder, pull down the Finder menu and choose “Preference” Click on the “Advanced” tab and pull down the menu under “When performing a search:”, selecting from the pulldown menu “Search the Current Folder” instead