The sent tab contains all the messages you have sent or replied to.
You can search by recipient to filter the messages.
To read the messages you will need to expand the link by clicking on it.
Scroll to read the entire message thread.
To delete the message select the red button in the action column or the check boxes and delete from the select action drop down menu. Messages are irretrievable once they are deleted, but the recipient will retain a copy until they choose to delete the message.