If you have registered your domain name elsewhere with another registrar and have an account with Mello Hosts.
Registrars are companies such as 123 Reg, GoDaddy, Square Space, Wix. You can edit the Domain Name records at your registrar to repoint your domain name towards the Mello Hosts Servers.
Edit the existing records or add them in.
Type Name Data TTL
A @ 91.238.162.110 600 seconds
Type Name Data TTL
A www 91.238.162.110 1 Hour
Make sure you have added your domain name to your account on Mello Hosts.
You can check the progress of you change with one of the many available free tools such as this https://www.whatsmydns.net/
You can of course transfer your Domain Name to Mello Hosts, if you are unsure how to do this then raise a ticket.
