If you would like to 'follow' a room just tap on the icon on the top of the screen that looks like an 'i' in a circle. Now tap on the 'follow' button on the room info page.
If you would like to 'unfollow' a room tap on your profile tab, and then tap the 'my rooms' button near the middle right of the screen.
A menu pops up that lists the rooms you are following. Tap on any room name in the list to view it's information page. If you want to un-follow a room tap on the 'unfollow' button on the left.