The "LIVE" area of TalkTalk is the place to see and join all the creator-hosted rooms.
If a room is LIVE, you will see a LIVE icon in red letters in a white box at the corner of the image. You can jump in and listen, you can also be invited to speak.
Whenever the host invites you to speak, you will receive a green popup message inviting you to speak. If you don't want to, you can tap on "Maybe Later".