Have you ever though how does it feels to be an left out? I changed some of my groups in school and being the new kid in the middle of the semester, I though I was going to be in that position, but I wasn't, If you re nice to people they are going to respond in good way.
Being the new one is never easy, being shy makes everything hard and also you'll be surprise for how many people are in the same position as you and also if you are feeling not as confident, remember that everyone can judge you but that doesn't mean that they are right, so don't let anybody get under your skin with out even getting to know you.
Being a new kid in 3 classes made me realised this, a smile opens doors, be nice to people and I promise that everything will go fine.