alright so this is what you do:
Before she gets there turn the fan or a little A/C on to make it just cold enough to put a blanket on both of you and don't be afraid to get close to her. Just see what she does when you bump her softly, but not too hard. Also try touching her feet with yours, kinda turn it into a game of footsie.
If you want to kiss her or start making out with her, you should get either a scary movie or a chick flick. The scary movie will have her in your arms (so you can get close and make a move) and the chick flick will get the romantic mood going (she might put her guard down and get close and look into your eyes and that's when you make your move)
And if you want to go the extra mile, have one of your friends text or call you in the middle of the movie and don't even look at who it is and put your phone away (this will show her that she is more important to you)
But the main thing to do is act natural. Girls hate guys trying to hard more than anything.