django - model for a messaging app between users

[Aamu Padi]

How do I go about creating a message app, between users. What's the business logic for creating the model? All I can think of was like this:

models.py

    class Message(models.Model):
        description = models.TextField()
        date_added = models.DateTimeField(default=datetime.now)
        sender = models.ForeignKey(User)
        recipient = models.ForeignKey(User)

I am not very sure if this is the way to go. If you could kindly guide me on how to get started, will be very thank full. Thank you!