You can build confidence if you have things like passion, desire, dedication, preparation, discipline, and direction. All these are interconnected.
Above all, desire and passion are crucial.
Understanding Confidence
I think the following words will give you the meaning of confidence:
"Confidence doesn't come out of nowhere. It's a result of something... hours and days and weeks and years of constant work and dedication." ~ Roger Staubach
"Confidence is the feeling you have before you understand the situation." - Anonymous