You own the domain with us and want to use on your server, go to domains and SSL:
Click on the domain and go to DNS:
Add record:
A record:
Point to domain to the server, hostname @ points to your IP address of the server and save:
Go to plesk and go to domains (this can look one of 2 ways):
Click add domain:
Fill in the add domain information and tick Secure the domain with Let’s Encrypt if you want to secure it with the plesk SSL. Create a domain user and password:
And that is your domain created in plesk.