How to make friend with people I have known for ages but have never been proper mates with?

Well after depression and some serious other problems I've had my social life has gone downhill. I now just about never see my mates outside school and I don't really have any 'close' friends. Sad eh? So how can I make friends / get 'tighter' with my mates? I've got a facebook and finally use my cell (starting on the 1st of dec) and I'm consciously trying to be more social. And especially how do I get tighter with people I have known for all my life at this school but I'm not really close to? A little background: I'm 13 going to high school next year. I've only got a few more weeks at my school. Any help is appreciated.