This technique allows you to create a beat or rhythm simply by increasing or decreasing the rate of the air flowing from your mouth, and into the didge.

While droning, practice blowing quicker or slower into the didge…

Keep in mind that the drone must continue!

See if you can keep a steady rhythm by doing this.

That leaves me with trying to explain the 'dog bark'.  The 'dog bark' is achieved by thrusting your tongue sharply forward, creating a popping sound.  It's the back of the tongue that forces air against the roof of your mouth that makes  the sound.