Going with crush to cinema- how do I act about it?

Well basically I asked the girl I really like to the cinema and I let her choose the film and she said she would meet me near the cinema we were going to so I just agreed. So on Sunday I'm meant to be going to watch this movie with her, but I don't know what I should do or say during the movie. Should I talk to her or let her enjoy the film? I don't want to make things awkward for either of us, but I want it to go well so she might see that I'm a great guy that he should be with or something like that. It will just be me and her, I offered her to ask someone else along if she wanted but she didn't want to. I know on TV that guys are smooth and try to get their arm round the girl, but I'm not that smooth and I don't know how she would react to that.
Going with crush to cinema- how do I act about it?
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