These concepts can be found in So You Want to Play the Clarinet or THE BREAK.
Intermediate Instructional Series
New Note Names - Not New Fingerings
Adding the register key to produce higher (clarion register) notes is easy! All you have to do is memorize new note names and attach those new note names to fingerings you already know. Do you know how to cross the bridge yet? Be sure to master that skill first before viewing this video.