We don't control your domain names, so you'll need to edit the DNS records on your domain's control panel.
You can either direct your domain at our services using a CNAME, or with A records. For an apex domain name, where you've just got the domain name and nothing below it like "www", e.g. "timpani.co.uk" you'll need to use the A record method.
You can find the IP address to use for your A record, or the CNAME in the Manage Domains section of the timpani panel. We provide your instance one of a set of IP addresses, so please set the IP as it's listed there, or you can use the CNAME tp-lb-vip.timpani.co.uk.
(Make sure to not use the 127.0.0.1 IP. That's special, it means "your local computer", or the computer you're using to read this text)