You may say:
Hello,Everyone.I'm so happy to meet all of you here.First,I want to introduce myself.My name is XXX,I come from .(Here you may use two or three sentences to talk about your hometown,in order to impress your friends and teachers.)
You also can tell them something about your character,hobbies,and so on.which book you like most?what do you want to do in your spare time?All such things you can talk about.Then you may find a good topic to talk with them.
Wish you good luck.
Lizzy