To restore files backups, you have to ensure that you have GNU tar of whatever version is available on your OS. Follow the usual rules for restoring from a GNU tar archive.
Be careful: handling below replaces each file with its "counterpart" in the archive, so be sure what you do.
sudo tar -xvpf /path/to/backup.tgz -C /As a result of executing this command, the files contained in the archive will be unpacked into the / directory, with their paths and access rights preserved and information about the extraction process displayed.