To read a message
Tap 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.
Google Talk Online Status
Tap the Contact's picture to open Quick Contact.
The Google Talk online status will appear next to the name of the sender of each message if the sender has a Google Account. Tap the contact’s picture to open Quick Contact.
After you archive or delete a conversation, you can tap Undo in the dialog box that appears at the bottom of the screen to undo the last action and restore the message to its previous location.
You can also swipe left and right across the screen to scroll though and read the messages in your Inbox (or the conversation list you’re working in).
Tap the Star icon
to mark it as important, the Reply icon 
to start a reply message to the sender, and the Options icon 
to provide access
to Reply all to reply to all addresses and Forward to forward the message to someone else.