Hi Richard.
When I did this a while back I did indeed use terminal and it was
very easy; you just use the "mv" or "cp" command, with which I
believe you are familiar. However, your default account should have
administrative privileges so you might want to check in system
Preferences User accounts whether you have admin privileges; usually
the default account does unless you deliberately make it otherwise.
You might also try repairing permissions with disk utility. However,
it's possible you don't need to put the sound file there; for some
programs, putting files in your home directory's Library/Sounds will
serve the purpose so you might try this first.
--
Cheryl
"Where your treasure is,
there will your heart be also".