From the Inbox, tap the New message icon (lower-right).
Tap COMPOSE (upper-right).
From the Recipient field, enter a 10-digit mobile number or a contact name. As the number or contact is entered, a matching contact may appear and can be selected at any time.
To add an attachment:
Tap the Attach icon (lower-left).
Locate then select the appropriate attachment. If necessary, select the attachment type (e.g., CAMERA, GALLERY, OTHER) located at the bottom.