How Could I Train For CROSS COUNTRY Next Fall :)!?

You need to start somewhere. Start small by running maybe a mile. YOU CANNOT SIT HOME ALL SUMMER. You need to get out there and work. Eventually after you can run a couple miles, start working out in a gym. Do different leg exercises to strengthen your legs. Keep running. As far as how fast you go: take a run, go with a good pace and bring a watch to time yourself. Each time you go out, try to beat this time. Eventually you will see your improvement and you will get faster. Also try running with someone faster than you, they will push you and you will get faster.