To open Messaging

Touch the Home Key , then touch Messaging Key in the Quick Keys bar.

The Messaging screen will open, where you can create a new message or open an ongoing message thread.
Touch New message to start a new text or multimedia message.
Touch an existing message thread to open it.

[Tip]

When a New Message notification pops up, choose to reply quickly without accessing the Messaging application by touching the Text field in the notification to respond with a text message, or touch Call to dial the contact or Delete to delete the message.