To schedule a message, click Schedule Msg on the left hand navigation menu.
This will take you to the Schedule page where you can then choose a contact or group in which to send a message:
Select the group by clicking the drop down box, or searching for a contact. Once the group or contact has been selected, the message box will appear where you can compose your message. Create your message in the text box where it says "Write your text here".
Compose your message and scroll down to choose the date and time.
You can also choose to make the message recurring. You can click the drop down box for more options on how the recurring text should send. Once you have the date and time chosen, click the blue "Schedule Text" box.