Hate to break it to you, but you can't just get someone to be self-confident.

There's two kinds of confidence that are worth having: 1- the kind that comes from accomplishment. There's just no faking this, you have to have succeeded at things to have this kind of confidence. Lots of people try to "positive think" their way to this confidence, but it's all a load of crap -- if you produce the results, you get the benefits. If you don't, you get to self-deceive. The former is obviously the way to go. 2- the kind that comes from being yourself. Everyone is a unique individual, but we come with varying degrees of complaints about ourselves. "I should be more X" is the general form of these complaints. The fewer of those one has, the more freedom they have to be themselves. Ironically, having the notion "I should be more self-confident" is actually useless with regard to #1 (you can't wish yourself into the confidence that comes from achievement) and counter-productive with regard to #2 (one more "should" on your list of what's wrong with you is not going to help matters). So in short, "be yourself and do your best" is about as good as it gets in this arena. Forget about trying to "be more confident".