You must be logged in to view the developer console. The login page is available at /.deliverance/login – you define the users using the server-settings configuration.
After you log in you can add ?deliv_log to any page URL to get a log at the bottom of the page. The log describes in detail how the page was transformed, including information about how the proxy was chosen and any subrequests. It also lets you browse the source involved, see what the selectors select in the content or theme, or get a list of interesting ids and classes in the content.