Be happy that you and your friend have each other at the very least
It isn't something that's gonna happen overnight. If you have a few people you are a little friendly with, get closer to them, and after you have a whole bunch of friends - well, you'll not even notice, but you'll have stopped being an outcast.
I can't explain it this way - the obvious thing is 'be friendly with everyone' - but in what way are you and your friends outcasts, if you can tell? That would help everyone in understanding and giving better advice.
A related piece of advice: If you're an outcast because your opinion and the opinion of the popular kids in school differ, don't ever change yourself over that. If, for example, they treat you like outcasts because you like, say, anime or a certain type of music, don't try to change your feelings towards stuff like that just to fit in. Being happy with yourself is better than being popular. You have your friend, who can sympathize, and that's a huge blessing.