If this is your first tournament then it will be very difficult to throw away the nerves. However, once you are actually fighting there will be no problem. Fighting in tournaments is, I think, good for people's confidence, because after the first two or three, you get used to being under pressure, and you have the experience to cope with it. So, try and suppress your nerves as much as possible this time, and each time you compete afterwards you will get a bit less nervous.
And don't forget, everybody is nervous about fighting in a tournament. It takes guts to get in there and give it your best, and the very fact that you are going to go do it despite your nerves is an achievement.