Hwo to know if she likes me and how to tell her that i like her?

ok, so i have like this girl since freshmen year, it is now halfway into our sophmore year, and i like her even more, but today i was at math tutoring, me and my friend were just joking an stuff, and she was staring at me the whole time laughing at my jokes, and during homeroom i always catch her staring at me, so do you think this means she likes me?, also, please tell me how to tell her how i feel, because we are both really shy, and im afraid that if i wait longer ill loose her,