Workspace members are assigned permissions to all files and folders when they are invited to join a workspace. Workspace Owners and Administrators can then restrict access to individual files and folders to specific users and teams.
To change a file's permissions go to the file's detail page by clicking on its title in the file list.
Click the 'Info' tab and you will see a Permissions link. In this case there are are no permissions set. Now click on the 'None set' link.
To change a folder's permissions, locate it in the 'Files' section of your workspace, click the folder's 'Options' button and select 'Edit permissions' from the drop down menu.
Restricting file and folder permissions
After accessing the permission settings for a file or folder a list of the users and teams that have access to that file or folder will appear.
To restrict a user's access select 'Read' for read only access or 'None' for no access at all; in this case the file or folder will not appear in the user's workspace. Click 'Update' to save any changes.