Please help! short! i dont know what to do?

i go to alot of baseball games with my bff cuz her dads the coach of this summer league highschool team. there is this guy there who is 17. im 15. and ive known him for a long time. but i havent seen him in like 5 yrs. so when i went to go say hi he was like "oh my god! how are you? how old are you?" and blah blah blah. i really like him now and i go to alot of their games because thats pretty much the only place i see him... what should i do to get him to notice me and want to ask me out?