It may sound counter intuitive, but a big part of being confident is simply not caring what other people think of you. You are you. You think certain things, you feel a certain way. If there's something you don't like in your life, you're working on getting it out of there. If someone else doesn't like something you do, well, who cares? What's important is how
you feel about
you.
Like, as long as you aren't hurting or killing people or anything.
Don't get me wrong, having other people's support is important for being happy emotionally, it just shouldn't be the end-all be-all of what makes you confident.
You don't have to drop bull crap to appear confident. Heck, you don't even have to know the answer all the time, or know what to do all the time. You're human, and as a result you're occasionally wrong. You may even make really bad decisions once in a blue moon. The difference between you and a poser is that you, as a confident person, own your mistakes. You accept them, and you may even regret them, but they aren't what make you. When you make a mistake, you analyze how you could have done better without beating yourself up about it or giving yourself unrealistic expectations. When you don't know how to handle a question that comes up, you do everything in your power to find the answer out for the person asking the question and be ready for next time.
You just have to accept that things are a certain way, and if something comes up and decisions must be made you'll do everything in your power to do what's right. You do everything in your power right now to prepare for the future. I'm not just talking about preparing for the end of the world or a medical emergency, but preparing yourself for life in the same way that you prepare for a hot date. Work on yourself until you're happy with what you see and do your best.
Something important to remember is that most people are the same as you: They're caught up in their heads with doubts, questions, and insecurities. The key to being confident is realizing that if you put yourself out there, the world won't explode. Heck, even if you blunder and fall on your face the people who laughed won't remember a week from now, doubly so if you laugh with them.
Don't be proud. Don't brag. Just be you, and don't be afraid to show others who you are.
How's this play into asking for a date? Realize that the girl (Or whatever) you're going to ask is a person. Know that between cultural expectations and their own shyness most folks won't ask you, and try to see things from their point of view. This person could very well be interested in you. Then again, they could be open to becoming interested in you through the course of a courtship.
What if she says no? you ask.
Well, who cares if she says no? Like I said, she's a person. She may be focusing on school, and dating would distract her from achieving her dreams. She may be dating someone else right now, which means that she's loyal and may even be open to it some day in the future*. She may even have zero interest in you, in which case it wouldn't work out anyways.
* Just don't suggest that you date if things don't work out between her and her boyfriend. That's a douche bag move right there.
Of course, it's just as likely that she'd love to date someone. She'd love to spend time socializing rather than sitting at home browsing Facebook. Maybe she's even been having a hard time and she needed someone to show interest in her. This skips a lot of guys' minds because of rejection anxiety, but being asked out is a
huge ego booster. It shows that people are interested in you, and it's nice because, culturally, girls are discouraged from being the one to ask the guy out.
So even if she says no, you'll go on with the knowledge that you lifted her day and made her feel better about herself. So asking chicks out on dates is kind of like doing your good deed for the day, and if it works out then it's even better for both you!
If she acts all offended that you asked her, well, she's a bitch and you dodged a bullet by getting that one out of the way fast. This is a whole 'nother topic, though. Just avoid crazy, and look for signs of rocky waters ASAP. If things don't look like they're going to work out it's best to bring it up honestly and quickly.
If you want some further reading material on confidence and asking girls to date, I highly recommend
Doctor Nerdlove. He talks about almost everything shy guys like us need to know about dating and stuff.