How do I know if he likes me?

theres this kid at school named devin. he is so cute and he is one of the first guys thst i actually liked. i dont know if he likes me back. he always is nice to me. he picks on everyone but me. my best friend likes him to but she doesnt know that i like him. is it okay if i ask him out? because usually a guy asks out a girl. please help me....i need to know!!!