What kind of training school is introverted or not? If you want to change, you can do it if you want to change. Introversion is not a day or two. You should be prepared for it. Then don't lose your mind.

If you can't change it yourself, try to contact the person who signed up for class. There are many projects in the application class, which are also for introverts, that is, to let you all get in touch with others, and there are some tasks that you need to complete. Over time, it can really change a person's introverted personality. Because he has that atmosphere in the training class.