The content you create should originate here, to ensure that it carries the "Private" settings for the group. The collection is subdivided into folders based on your sub-group/partner assignments that were made during your work in July.
To upload content, locate and select your folder in this collection. Click the "Build Up" link, and follow the prompts to insert your resources. If you accidentally insert them into the overall collection and not the folder, you can move them to the right place by clicking on the collection's "Organize" link.
Note that the metadata settings (or descriptive tags) of the collection -- the subject area, educational level, and the access/license -- will be inherited by the folders and the resources you create within this collection. You will need to add the title, description, and instructional component type for your resource. You may also edit any of the inherited tags for your content without impacting any other resources within the collection.