Just like you, I'm the person who can't stand social contact or small chit-chat, which basically describes an introvert. Don't worry, what opened up my personality little by little was to do community service because the people there either just see you or praise you for your talent, hard work, and/or service. That's a great way to become more social. You can also join clubs (not only at school) and meet people there who have the same interest(s) as you~

Quiet people tend to embrace conversations when they're in a comfortable environment, so it's possibly not a good idea to start at parties (unless there are people there you know).

As for the confidence part, it's up to you to build that up. It's all about a person's comfort zone, and it varies in people. Also, (this might be a topic change), as quiet people we can observe how other people behave and converse, so you'll learn something from them~! Be free like this penguin~! ^_^