Shy is fine. Quiet confidence is good. (Think strong, silent type.) Confidence is the quality of being comfortable with yourself and having a sense of certainty of your value. (I am guessing that this is a quality valued by the male species, too.) It is sometimes hard to know how to convey this quality, but it becomes more natural with age, so don't be too hard on yourself, and keep practicing.

Loud, outgoing confidence looks more like arrogance, and well, that can be very alienating. It's a fine line. Good luck.