First, to view your incoming messages go to ADD-ONS > TEXT-TO-SCREEN. Once there, click the screen button (
) next to your text-to-screen. Here you'll find all of your PENDING messages. For any message that has come in, you can choose to accept or reject a message as shown below.
To view your accepted (Live) or rejected (Archive) messages simply choose the appropriate link at the top next to View Messages.