Just go with whatever you feel is right, dude. Things might sound complicated but most of the time they're not that bad. I would tell her how you feel if you feel comfortable enough. If not, just be a nice guy to her. I'm not saying you have to do a bunch of favors for her or anything, or go to great lengths to show your affection. Just be yourself, man. It'll make you seem more genuine and chicks tend to dig that.
Or you can wait till high school. In my experience, things have gotten a lot less confusing with relationships and love interests as i reached my current year (junior).