To view your sent messages, click Outbox from the left navigation.
You'll be displayed a list of all your outgoing messages. Use the Search and filter options to find the message or messages you desire.
If you wish to see your more details about your message, as well as delivery information, click "View Report" next to the desired message.
You can view your scheduled messages by clicking the "Scheduled" texts tab at the top of the page. As these have yet to be sent, you can edit or delete these messages, however there will be no delivery information available until they are sent.