i dont know how to talk to this guy

Ok so there's this guy in my class, he's kinda cute and I think he's always been attracted to me since the beginning of the semester as I see him staring at me all the times. Sometimes he sees me walking on campus and when I look his way, I immediately catch his eyes looking directly into my eyes. We have 2 classes together, and he sits right next to me in 1 class but we barely talk. He seems to be shy, just around me tho, cuz he has no problem talking to other girls. Although we did talk like twice, but it's just him askin me how the course goes and stuff, nothing much. He never says hi or anything when he sees me in the first class ( we have 2 back to back classes together), and when he bumped into me on campus he doesnt hi either, he just looks at me. I feel like he doesnt really know what to say. I heard that he's nice and cool and he's cute so I just want to be friends with him cuz I know he has a gf already. I don't really have a thing for him cuz I don't really know him but I think having him as a friend would be great. So the next time I see him in class wat should I say? Just to build a friendship w him, nothing special. And my problem is that I always seem to be a lil flirty and guys misunderstands me. CUz I think flirting is fun and I cant help it but for me it doesnt mean that I like him. So wat should I say durin the convo not to be flirty and all? Thank you!