Type a brief message. Type your name. After you send the message you will go back to the main menu. To read your messages, type I for index. Use your down arrow to get to the message you want to read, then hit enter.
Further instructions are on the bottom of the screen.
You may have to return to the main menu first. There are a lot of other features in pine, but these will get you started. There are usually a list of options at the bottom of the screen. To get out of alpha, type exit at the prompt.