To read a message
Touch a conversation that contains the message you want to read.
The conversation opens to the first new (unread) message, or to the first starred message, if you’ve previously starred a message in the conversation.
The Google Talk online status will appear next to the name of the sender of each message if the sender has a Google Account. Touch the contact’s picture to open Quick Contact.
While reading messages in a conversation, you can use the keys at the bottom of the screen to archive the entire conversation or delete it. After you delete a conversation, you can touch Undo in the green bar that appears at the top of the screen to undo the last action and restore the message to its previous location.
You can also touch the arrow keys 
/ 
at the bottom
of the screen to read the next, oldest, unread message in a conversation
in your Inbox (or the conversation list you’re working in).
Touch the message actions icon 
on the message header to access message actions options which include 
to mark it as important, 
to reply to the sender, 
to reply to all addressees,
and 
to forward the message
to someone else.