I think they would try their best to avoid being in a situation where they meet new people. But if it is a must, and unavoidable, they will mostly listen, and not talk about themselves (or much else) till they get comfortable with another new person.
But this does not mean that an introvert does not have anything to talk about. He is just not used to talking about it as much as an extrovert might be. I have had conversations with self-confessed introverts that were very, very interesting- sometimes longer than those with extroverts.
So make the introvert feel comfortable, and they will open up. May require more patience than you normally have. If you have an introvert as a friend, you may not even notice that they are one. Maybe, just maybe, social media are one place where an introvert gets an equal opportunity to be social.