Learn about the tip, middle and back of the tongue. Articulations are created with the tip of the tongue. Density of tone is controlled by the middle of the tongue. The register of the notes changes the position of the back of the tongue.
Practice saying the sound "dee" and notice how your lips, mouth and tongue move. Once you know what this feels like, practice saying the sound without vocalizing.
Place the clarinet in the appropriate position to play. Curve the bottom lip over the lower teeth, place the mouthpiece just inside your mouth and rest your top teeth on the top of the mouthpiece. Wrap your upper lips over the mouthpiece to form a seal.
Articulate by pronouncing the sound "dee" without vocalizing and allow the tip of your tongue to lightly touch the reed. The middle of your tongue should lie flat, and the back of the tongue should be relaxed.
Practice tonguing slowly at first and gradually increase the speed as you develop your technique and skill.