How do I know if a guy likes me?

This guy named Seal is in my homeroom and I never really been attracted to him at all until now. Every now and then(once a week) he would talk to me and few little times he would come by my desk and he would steal a few paper from me and give me a little smile( not a one you could actually see). The problem is I go with his friend Johnny and he is now going with my friend. I told my friend I like him and now that they're together I'm afriad she would tell. Is he trying to make me jealous? Or does he like me at all? HELP!!!!!!!!!!!!!!!!!!!