when you add files, they are NOT copied, they are just "linked".
it is all virtual, that's why it is called virtual file system.
if you want to upload you have to use "real folders".
you can add a folder, and see it will ask for virtual/real.
if you really want to upload to / and not into a sub-folder, you can use right click on the root and "bind root to real-folder", available only in expert mode.