How to add a second domain to DigitalOcean (Ajenti V)?

Question

Domain name market

Good day. There is a site on vps digitalocean (ajenti v). I must say right away that another person set up and installed the site, with whom it is no longer possible to contact.
You need to add a second site to the same account in DO. How to do it? And another question, how to backup a site in Ajenti V?
Thank you.