I am a sophmore and i run cross country.?

This is my first year doing a sport ever.My time is 18:00. I've been really disappointed in the way i ran. I feel like i can do better but i never do better. I want to break 15 minutes next year for cross country. That sounds like a longshot but a lot of people say i have potential. What should i do to make that happen. What kind of training should i do in the summer.