Pages that are published in a collection will mimic the visibility settings for the collection they belong to. So if the collection is not published to the public or to a group, the pages inside will not be visible to the public or group.
To change the visibility settings for a collection when publishing:
1. Click on the "More" icon beneath your collection description.
2. Click the "How To Publish" icon.
3. A window will pop up to outline the available publishing options.