we have a few older students in our class - I'm the opposite I am years younger than anyone else and at first I felt out of it and people were a bit apprehensive speaking to me. But maybe I'm lucky, we do lots of stuff where we have to work in smaller groups and together a lot and everyone becomes good friends by being made to work with each other.
I was always the outcast at school and I am now a nerd and proud of it.
It is hard in the beginning to initiate the conversations but once people get to know you it gets better. Not all the people in you class are like Barbie dolls are they? Maybe try to befriend some of the quieter, less noticable 'nerdy' people, that's what I do. They are often feeling the same as you and too shy to initiate things (i know i did)
And remember you don't need to get along with everyone or even most people in your class, you just need a couple of good friends to help with study etc and the best people for that are the quiet ones.