How to flirt with a guy at work?

I've just started working at McDonalds, I've only done about two shifts and there is this one guy, I haven't talked to him but I've caught him looking at me. I was doing the fries and all he did was elbow me while he was doing his job which was extremely annoying and no matter what he did it, even after obviously noticing. I don't know how to approach him or even flirt with him. How do I do these things? I'm not a confident girl and I'm pretty sure he is older then me just like one or two years. Thanks :)