From this video you'll learn how to arrange, mute and hide your channels. You'll also get a short introduction of the channel management section.
The "Manage" section stores all the channels that you have access to. The active tab shows your active channels and displays if the channel is a primary news channel or secondary news channel.
From the tabs you can also see all the hidden and archived channels. This is also the easiest place to unhide or unarchive channels.