i lead him on...

there's a guy in my class and he's nice and one of my first guy "friends" (more like acquaintance) ever but my friend says she's pretty sure he has a crush on me because i flirt with him? i'm NOT trying to flirt at all i never realized that maybe the way i act with female friends is seen as flirtatious with boys? i don't even know what flirting is!! i'm 15!! i don't even know if he likes me!! i guess i see it now and and i can see it in his i act around him because i'm naturally very giggly but i'm stressed i don't want to lead him on.