Brand Admins can add a Dashboard to their Brand Portal by selecting "Dashboard Settings" from the "Settings" Menu of the left toolbar.
If this is your first time creating a dashboard, you will be presented with a dialog asking if you want to create a page:
You will enter into a starter dashboard in Edit mode.
Note that your dashboard will not be live until you toggle "Published to be on".
When published, the "Home" icon for your portal will bring you to this page.