This guide explains how to locate your configuration files, both using the alias Abr suggests (the easiest way to locate your live config) and by path (which you'll need to use to find your them in your backup):
How to backup or locate your Opus configuration (Simple) (see the Locating the config files by hand section).
If you manually copy your old config backup to your live system, make sure you fully exit Opus (via File / Exit Directory Opus) first. (Do not just close all windows. That won't normally exit the program.) If you copy the config while Opus is running then some of the changes will be ignored and overwritten the next time Opus exits.