I need help with a guy. he talks to me constently, agrees with me a lot, comes and sits with me at lunch a lot

he says i'm really smart, smarter than him [whish is a compliment since he's had all A's since 3rd grade].and 2 days ago i found out that he's been dating this girl that i hate for 3 years just to make me jelous. i need to make a move at the football game tonight because my bff blurted out that the reason i was all fidgety in homeroom this morning was because i like him and he just sat there and smiled until i denied it because i don't think he likes me. what do i do to let him know i like him?