I like everyone is saying practice, practice, practice! Another thing that helped me with speaking in front of large groups was once I practice and felt that I knew my speech exactly. I would gather all my friends family, basically as many people as I could get. It is impotent to have both of people you do not know and people you know. That way when you present our speech you will get the same nervous feeling and see where you will make mistakes and practice more on those parts. Good luck and just remember that you can get over this fear over time but you have to keep doing it.