To put it bluntly, let your shoulders reach behind your shoulders as far as possible under the condition of natural relaxation. Try to get your shoulder blades together. Just like the model on the runway, hold your chest out and try to show the neck and below the clavicle.

Method 1: Put your back against the wall, make fists with both hands, close them and put them on your waist, but stick your ass and back to the wall. Please press your shoulder against the wall as much as possible. This is the best way to open your shoulder.

Method 2: Face the wall, preferably stick it on the wall, grab it with both hands and lift it up, then ask someone (preferably someone who has practiced dancing) to put his knees on your back and pull his hands back.

However, don't rush for success. Although there is no harm in opening the ligament, it needs a gradual adaptation process. Don't strain the ligament. This is not worth the loss. Finally, I hope you can dance better and better.