Moving from Joomla to Wix CMS

We've been using Joomla as our CMS and now we're moving to Wix. How do we 1. make the move in cpanel, (domain: example.org) 2. keep the original Joomla as a backup, (domain backup.example.org) 3. create a sandbox where changes can be made and previewed before being promoted to the main domain)? Thank you.