Dude,

The best way to do this, is by starting "small-talk". Just start saying 'hello' or talk about the weather when you meet new people in the elevator.

When you go to Mcdonals and other places, don't just order, ask them how they are doing? you know? small things?? I am sure you will find it a lot easier to talk to younger people and people who are in your level like hapsis and mexicans or janitors (no pun intended) or people in customer service, who like talking - or they HAVE to talk to you.

Or if you are student, if you can't speak up in class, talk to the Prof after class. I really recommend asking questions in class, because that takes a lot of courage. If nothing else, just raise your hand and say "Prof, i am not following, could we go over this one more time". Try this out a couple of times, this is a good way to build your confidence.

Or join those clubs, what's that called "kettle class" or "tea party" or something, where you go to meet new people who want to learn public speaking. WTF, I can't think of that word right now. But you get the idea.

Good luck.