How do I copy a portion of one scene to another?

I want to move a portion of a scene to another scene because I think the scene is too long. Is there a tool for this, or do I have to copy it over by hand?

You can copy a whole scene but not portions. You need to go on the scene selector. Right click the scene that you want to copy and press duplicate. Give your new scene a name and you are done copying! Remember: You can delete loads of tiles at once so don't worry about taking time to delete the parts you don't want.