Click the Filter icon at the top of the Conversation List to create a new view that fits your needs.

At the moment, you can filter the list to show all Conversations (default view), My Conversations (the ones you’ve claimed), New + My Conversations (unclaimed Conversations plus Conversations you've claimed), or Unresolved Conversations. You can also sort the list by Most Recent (Conversations with the most recent activity) or Longest Wait (Conversations where the contact has waited for the longest for a response to their last message).

Watch tutorial on the Conversation List here and tutorial on messaging basics here.