Don't be shy.
Present at meetings: team meetings; management meetings; teleconferences with colleagues or customers from other parts of the world; to clients at your office or their office; and at conferences, workshops and trade shows.
Step out of your comfort zone. Practice your presentation until you are confident to present it to a friend, family member, or work colleague (test subjects).
Sure, many people feel nervous when we present in front of an audience, however, make sure that you hold your confidence in your voice to get through. You make your own confidence. That's you. Be proud of who you are.
They hired you because you can. In many cases, can't is a poor excuse.
Get out there. It's an experience.