How to edit and film with iPhone 5?

Me and my friends want to do a prank and we will be filming with iPhone 5… Do we just film the whole prank and cut out bits? And on what FREE editing software? And will the sound be okay?

I'm not that good on making films, but I've made some short movies and if you're not really interested in making like special-effects etc and just cut out bits then you maybe should use like Windows movie maker or something like that, because that's easy to handle.

You can edit the video a little bit right on the phone itself.
Or, use quicktime once you get the video back onto your computer

You could also download the imovie app - it's very cool