Note that usually you just type 'w' without a file name,
and the editor buffer is written on the 'current file'.
What is the 'current file' when you have executed an 'r'
command? Well, it doesn't change. But rather than
be in doubt, there is a command
which prints the current file name.
You can change the current file name with
so that you can copy file 'old' to 'new' with
Try that: copy file 'first' to 'second' in this
directory. Then type "ready".