I need help with splitting and copy and pasting scenes.I also want to add audio.
I don't believe Natron has audio support. You could theoretically edit clips together with Natron, but you'd be far better off using Blender's NLE, Flowblade, (if on Windows) Hitfilm, Davinci Resolve, or some other similar program.
Ok, Natron does not support audio. Here's a post that talks about it: https://forum.natron.fr/t/editing-in-natron-with-audio-playback/1121