Before you start, make sure you have bought a domain for your new website. This should be something like website.com. You can purchase domains from many different places, including, https://www.123-reg.com/.
Log in to the control panel of where your domain names are registered - in this example, we have used 123-reg although most providers will be similar. Navigate to the correct domain and then choose "Manage DNS (A, MX, CNAME, TXT, SRV)".
You should now set a CNAME record for your Umbraco Cloud provided URL (e.g. website.s1.umbraco.io) and an A record for the Umbraco Cloud IP 220.127.116.11.
Log in to the Umbraco Cloud Portal (https://umbraco.io).
Go to the project you wish to configure.
From the 'Settings' dropdown in the top right of the project dashboard select 'Hostnames'.
In the field provided add all of the hostnames for your new website, e.g.
Refresh the page 'Hostnames' on Umbraco Cloud. If set up correctly, each domain should display the phrase 'Protected by Latch' to the right-hand side.