Files can have security added to them in the File library.
The security must be set to each file individually.

To set security for a file that has been uploaded to NetCommunity:
  1. Log into NetCommunity as a administrator
  2. Go to: Site Explorer > Files
  3. Find the file that you want secured/password protected.
  4. Click the pencil next to the file name to edit it's properties.
  5. Click the Targeting & Security tab.
  6. Click: Add users and roles.
  7. Search for the Role (user group) or individual user you want to have access to the file.
  8. Click on the Role/User to highlight it.
  9. Under: Assign permissions, put a check next to the privileges the user will have when accessing the file: View, edit, etc...
  10. Click the Add button to add the Role/Individual.
  11. Repeat until you have added all of the desired Roles/Individuals that are to have access to the file.
  12. Click: OK.
  13. You will be returned to the Targeting and Security page.
  14. Make sure the options for the default User/Role Name: "Everyone" are UNCHECKED.
  15. Click Save.
Now only users that were added through Roles or Individually will have access to those files when logged in.
If a user that is not logged in tries to access the file, they will be prompted to log in before they can view it.