There are two options:
You can only change your domain Name Servers to ours, we have anycast DDoS protected DNS, in this case you can use provided cPanel account to manage your DNS records and use our free email service. All DNS records are already configured in this case and you don't need more action.
You should go to your DNS server, elsewhere you manage your DNS records and Add or Edit your domain A records to our reverse proxy IP. In this case you can't use our free DNS management and email service.