Because it's all new for me.
Ah well trust me there is nothing to be nervous about. I was a little nervous too on my first day and a little before, but just try going into the first day thinking everything will be awesome. It will be alright. Also try and open up a bit to people in your classes. It makes it so much more enjoyable if you try not to be shy. I was pretty shy my first year, but now I've opened up a lot over the last 2 years.