“I am so shy in groups. My thoughts and opinions disappear from my brain because. I get so nervous. I asdfadsf ”

Socialize with a friend who introduces you around & ask you what you think when you're not talking. It just takes practice. You developed a fashion sense (or could have) by paying attention to what people wear. So develop a social sense from watching people, too. A lot of people are hesitant in groups. You're not alone, so don't feel indicate! Just think of yourself as a student! You can do it!