Here's how you can make file folders publicly linkable from within a private Groupsite:
1. Log-in to your Groupsite (as a manager)
2. Select the SHARE tab
3. Select the File Cabinet subtab
4. To the right of each folder name you will see a cog wheel icon (visible only to managers) . Click the cog wheel.

5. Select "Folder Properties" from the drop-down.

6. In the pop-up window, under the "folder Visibilty" drop-down list, select "Non-Members can view (download) files

Any files (including images) that you want to be visible to non-group members should be kept in a file folder with these properties.
Examples are:
1. Any images that you want displayed on your SUMMARY page that you want to be visible to people who have not joined or haven;'t logged-in yet.
2. Images you want embedded in email blasts (members recieving emails who are not-logged in will not see images unless they are stored in a folder with the above properties).