We have learned more about how to keep our content private using space permissions and page restrictions. Confluence has a hierarchical permission structure starting with super users who are allowed to change all permissions and view all content. With regard to security, a good rule to follow is to limit the number of users with administrative access to an absolute minimum.
It's important to note that restricting permissions can help to limit access to content that you create, but this works against the intended use and benefits of the application. Confluence is a wiki and as such is intended to encourage collaboration and sharing. Keep this in mind when you limit access to areas of your Confluence instance to specific users and groups.
The next chapter will go into customizing the look and feel of Confluence, so that it incorporates your company's branding.