First off, I know how you feel. Totally. I used to be such a shy person when it came to strangers and dreaded the first day of school. But after transferring to a new school (for college), I knew I had to face reality and be over my fear.
So, here's how I went about it.
The teacher didn't let us do any partnering activities but instead, called us up one by one. I was the last, for some reason. Anyway, he had already given us a "template" - he told us what we should say and stuff.
Basically, it was just general information. Like your name, age, course/year, from where do you come from (previous school), where do you live, hobbies & interests, etc...
It was nerve-racking at first, but you'll get used to it - think of it like this, all of you in the classroom are freshmen. All you guys are scared shizz and nervous. And it's not like any of your classmates are really listening to you because they're scared. Even that one person who didn't seem to nervous or scared, is actually, also scared & nervous.
Take a deep breath, relax yourself and wing it. If you need to write it down, then do so. But don't like, read from the paper. You can write down keywords or things like that on a small sheet of paper.
Or you can make the class laugh to lighten the mood, like I did. However, you should do this with caution because some teachers don't have a sense of humour. I made the class laugh and it resulted to my name being on my teacher's black book. :/ Which I didn't think was so bad, since I looked at it in a positive way.
For group activities or partnered activities, you should remember that your partner is just as scared and nervous as you are. Take a deep breath & smile. No, not a psycho smile but a friendly smile. You can smile shyly to lighten the mood - once your partner sees you're just as nervous or shy, s/he'll relax a bit and so will you. Trust me.
Take the initiative to talk to your partner because it'll calm you down faster than if you don't. You can even tell your partner that you're nervous or scared or shy and in no time, you two will bond over that - giggle/laugh - and once you two are familiar with each other, once it's your turn to share to the rest of the class, you'll just be giggling and saying that you're both nervous or something. It's not bad, in my opinion, since it's the first day of class.
But mind you, don't forget to ask your partner's name AFTER you introduced yourself - else you won't have anything but "nervous" to share to the class.
Another tip, if you guys don't know what to talk about - then talk about the basics/generals. Name, age, birthday, zodiac sign, interest, hobbies, school, music, movies, books, animals, etc. - just please don't talk about the weather unless it's very significant, like, a typhoon or something. The weather, unless significant, is such an awkward topic, I swear.
So, I don't know if that was any helpful to you - I hope it was. And I wish you immense good luck during your first day of classes. :3
If you need any more advice, you can always e-mail me or ring me up at Messenger. :3
(I have this soft spot in my heart for freshmen... 'Coz you guys are really young and cute~)