Basically, it's a breathing technique. The first few days of the course you are thaught to talk with your hands on your ribs. When you inhale, you should expand your ribs/lungs as far as possible, to make sure your diafram has enough room to straighten out in a fluent motion. Then when you exhale and talk, you should use your hands to push your ribs inwards. This will cause your diafram to fold and go up (I couldn't figure out how to explain that part in English, I hope you get it) in a fluent motion. If that happens you should be able to talk without stuttering. Then after a few days you are thaught to picture the movements your diafram is supposed to make on the wall or wherever you're looking at, with one hand in front of your chest to help with the visualisation. And then a few days after that you can take your hand away and, while still focusing on what you have to do ofcourse, speak and behave a little more natural and freely. Then there are breathing excersises, 5 minutes each, which you have to do right after you wake up and right before you go to sleep. The purpose of those excersises is to train everything I have tried to explain above.