First and foremost, you've taken an initial step in trying to overcome you problem. You're talking amongst friends. Now then, you seem to handle yourself very well on the internet, so that can be a start.
You see, sometimes if you can mimic what you do on here, it's relatively easy to do it in person. I used to be in the same shoes as you when I was younger. What I did was put myself amongst a lot of people, not necessarily in a social gathering, and mingled. Little by little, the shyness of being around people gradually wore down cuz I got used to be around people a lot. You should seriously think of being around people more and you will see how comfortable you get when you no longer worry about what is going to happen.
Also, try not to be self conscious like worrying if something you say or do will go wrong. Nothing helps like being able to laugh at oneself.