If you haven’t made any changes to your theme files then you can download the updated version and it should work without having to deal with adding/replacing code. You can download it from your account – https://appfinite.com/my-account
If you want to manually add the code you can use a tutorial. Here is one I’ve seen a lot of people use – http://wpbacon.com/tutorials/genesis-responsive-menu-2-0/
Let me know if you get it working, or if you need assistance.