If there are multiple users on your Mac, other user will be able to view the folders (the custom folder that you created, not the system folders) on your account’s directory. While they are not able to write to it or make changes to the files within the folder, they are able to view and read the file within. Here is how you can make your folder private in Mac OS X.
1. Open Finder. Select the folder that you want to make private. Right click and select “Get Info”.
2. At the bottom of the Info window, under the Sharing & Permissions section, change the Privilege for “everyone” to “No Access”.
Close the Info window. That’s it. Other users will not be able to view your folders now.