I'm glad you asked!

I'm an extrovert. All though my youth, I told myself I was an introvert because I spent a lot of time by myself, but the truth was that I didn't like spending time alone -- I just had to because I didn't have any friends. Didn't go to a single high school dance, didn't play any sports, didn't join any clubs -- not because I was physically incapable, but because I couldn't bring myself to walk through the door, buy the ticket, or talk to people that were involved. It was very very sad.

After a medical issue forced me to drop out of high school, and after a period of crippling depression, I realized that I could stop being so miserable if I just got up and did something about it. This phenomenon follows me to this day: if I have some kind of project or issue that needs to be resolved, I'll wallow around in self-pity for an eternity until something clicks and I decide to get it done. Once that happened, I started looking for opportunities.

I had been spending a lot of time goofing off in online forums, and I was one of those guys that was excellent with people (especially the ladies) as long as it was typed out ahead of time, but in person I couldn't function. Now, I didn't have any friends, I wasn't in school, and I wasn't working, so meeting people was difficult, but I ended up getting close to someone on one of the forums. Posts became PMs, PMs became IMs, IMs became phone calls, phone calls became Skype. She and I got ridiculously familiar. In a way, this girl was a training dummy for me socially.

She happened to live in a city across the country I'd been wanting to move to all my life, so once I turned 18 and hauled ass over there I already had a friend. She was very understanding of my pitiful awkwardness, and once I realized I could make her happy it became easier to try to talk to other people too.

So I met friends at work, got into college and met friends there, and I found that after I'd gotten used to talking to one person in real life besides my immediate family, the rest just fell like dominoes. The more people I talked to, the faster the momentum picked up.

Confidence is something you can start out faking, but eventually it becomes second-nature. All you need to do is make one friend -- and the Internet is a great place to do that, as long as you find a closer-knit community than, say, AskReddit -- and you can use the experience from that friendship in the rest of your life.

Oh, side note, you can get extra confident if you're excellent in bed. I can only speak for guys, but fellow dudes: If you start having sex with a lady, and you actually give a shit about her, there's a depressingly good chance you'll be the best she's ever had. That's all you really need to know about sex, the rest is hammered out in practice.