How to get in shape for volleyball and track? improving skills?

I'm getting really into sports and athletics this year and i'm in 9th.I did volleyball in 6th but 7th and 8th coudlnt' participate because I had surgery and had to wear splints but i got the okay the end of last year to participate in anything. Volley ball starts in the fall, and track this time next year. I want to start getting in shape for them now though. Give me any advice to help get stronger, healthier and improve my skills in both areas. I'm not totally out of shape, i'm 15, 96 lbs, 5'4", i ride my bike a lot, used to have asthma but it pretty much disappeared. Thank you'