How to restore games?

Hello,
I've had some trouble with the torchlight demo crashing, so I backed it up, deleted the local content, and now I want to restore it to avoid re-downloading it.

The back-up wizard said I should either run the "first file" or the backup/restore wizard.

The files are not a file that the system recognizes, nor can I open them with Steam.app, and when running the "backup/restore games" command from the "Account" menu, all it does is display a message "You don't currently have any games ready to backup.".

Does anyone know how to restore backed up games in steam for mac?