Public content refers to OTU/content text that has been "published". This content is available in public views.
To make your content visible to the public goto
and choose the template (via the "compare content OR show page:" dropdown) that contains the content you want to publish. Then click on the 'edit' link to edit our review your content, you will see a 'is_public' check box for text field. If the box is checked then when 'publish' is clicked that content (and all the figures associated with it) gets duplicated to a public version of the page.
Note- once you publish a page you create a static copy of that page. Further updates to the content is not made public until you "publish" again.