different guys act differently, i myself laugh at whatever the girl i like says and stare at her alot. some guys dont do anything at all, so you should give hints to them like laugh at their jokes always be near them in school if you can, or be really nice to them. some guys (such as the retarted jock freaks) act stupid around girls and make lame jokes (wich usually drives girls away0 so look for these things and he might like you.( be in mind some guys act this way normally or just think of you as a friend)
It is ok to like a guy after you know he likes you. That is perfectly normal and a part of life.
If a guy likes you but you don't know him he may look at you or walk by you whenever possible.
Not sure how you expect someone to magically know something.
If he says i like you
This is a tongue twister. And no.
If a guy likes you he will flirt with you but if he doesnt like you then he would act like he hates you.
if he acts like he doesn't
Ask him
You wait.
nothing! they maybe know that the guy you like likes you back!
kis and do it
Break the silence, Get to know him a little bit if you like him and he likes you