Out in public, how to do it

Why do I focus so much on other people and what they think about me when I'm in public. I want to get my hair done but I can't leave the house. I don't want to go get my ticket for the train and be waiting around with others and standing beside others on the train. I never know how to act in public and I feel uncomfortable. Why is my life like this? Everyone else is out doing what they need to do and want to do and I can't go anywhere where there's people.