YOU ask him out, unless he's fast enough and asks you out, but still, YOU need to take the initiative, and if you don't know what that means then look it up! But if u dont suck his cock fast he wont
he should ask you out. he may not like you and then all you have done is thrown yourself at someone that wants nothing to do with a relationship with you.
If you have known him for a long time, and you have developed feelings for him, find one of his friends and ask who he likes, and then work it out from there. If you want to find out, just try asking...