How can I stop worrying so much and end my shyness?

I've been a shy male ever since childhood and it's something that always been a challenge to overcome. I always worry what others might think of me when I speak in front of groups. Sometimes when I have something important to say in a group, I usually keep it to myself, fearing embarment and too much attention. One day, I want to just end it all and become a very outspoken individual and have a leadership-style personality. In my job in the IT field, I know it's required if I wanna move up the ladder and be promoted. What first steps can I take to overcome this tough challenge?