I like this guy what do i do?

well i like this guy and always wen he walks by i look at him and he looks at me but when i ask him or my friends ask him out for me he says no because he likes a girl in my cla and i even asked the girl will she go wif him and she said no but i realy like him and wen i ask himhe says i still like this girl and its really close to valentines day should i give him a card or something or wat should i do plz help i really like him