"Can I use this in my video?" Unfortunately, I don't own any of the rights for the music I feature on New Youtube Videos, so you'd have to ask the artist.
"Is this copyright free?" Again, it's not up to me, I don’t really know if it’s copyright free or not and I don’t receive any permissions for my uploads.
"Do you make the music?" No, I only feature music I like.
"Where do you get your backgrounds?" Unsplash or Adobe Stock. All backgrounds I use in the videos are paid/licensed or royalty free.