How do I flirt with him?

I personally don't like movies as a 'relationship builder' kind of date, simply because you're so limited, conversationally for the most part, in what you can do and say. Movie theaters are really hard to flirt in, but you can get some sparks going.

But, if it must take place in a movie theater I've got a few tips.

First, consider yourself lucky because you know this guy is into you, so you don't have to work on the attraction angle all that much. Of course never do anything outside your comfort zone.

1. Lean on him: My first girlfriend and I were in the same spot you two are (nervous, movies, know we like eachother) and this was the approach she took, just leaning against me and putting some weight on my shoulder. This works well because it shows physical comfort without doing anything drastic, but primarily it shows him that you're okay with some form of physical contact from him. Basically, you've now given him permission to put his hand around your shoulder, hold your hand, and do all the other menial things that some guys are terrified to try until they know for certain its alright.

2. Rest your head on his shoulder: This works well with leaning on him, it has all the same effects but is a little more intimate and cuddly. Also this is a rather awkward position for the guy so he's more likely to put his arm around you simply because it feels more natural than just sitting there like a lump.

3: Hold hands: Your hands have a fun little way of being active even when your mind is wondering around doing other things. Ever twiddled your thumbs, absent mindedly played with a pencil, or any other various hand movements you do during class that serve no real purpose? The same thing happens when you hold hands with somebody. Unless you're both horrified to be touching each other, your hands will naturally adjust, squeeze and 'play' with each other. Its subliminal but its something.

4 Share popcorn: Pretty easy to understand why this one works.

Its getting long winded so I'm gonna kill it here, hope this helps.