Find a hobby that involves other people.
Talk to people at work or school.
Actively try to solve your own problems. Read self-help books and really consider the opinions of the writer. Make yourself go do the things you feel anxious about. Smile. Find a reason to smile. Be less judgmental of other people and realize no one is look at you and their opinions don’t mean anything anyways to you.
Also, examine your opinions of what “social” mean and if they’re really necessary. I don’t go to clubs because I find yelling over loud music about video games sounds retarded.
Do what makes you happy. The rest will follow. People like being around happy, accepting people. People don’t like being around moody, exclusive people. Widen your horizons.