How can I tell if he likes me?

Ok so im in high school and theres this guy and he's in pratically all my cles. I really like him and I think he might like me but im not sure, I also think he might like my friend but I really dont know. What can I do to see if he likes me. I'm more on the shy side when it comes to boys so it all has to be a little discreet. Thanks!