Restrict Access To One Folder?



My friend and I have a folder set up where we can just share files together, with unattended access via file transfer. This was, we dont have to worry about anything.

However, we would like it so that he can only access ONE SPECIFIC FOLDER on my PC, that was if (God forbid) he decides to do harm, he can only get to this one folder.

IE: He requets access, but he can only see and move items into/out of one folder that I set.

Is there a way to make sure the person on the other end of the file transfer can only get to one specific folder? Can you lock others folders or whitelist only one?

If I need to clarify, I will.