It's easy to set up a new DNS zone from scratch in the NS1 portal. First, though, confirm you don't have the ability to get a zone file, which can save some effort.
Navigate over to the Zones section of the NS1 portal, and click "Add Zone", then pick "Normal Setup".
Enter your domain name. If necessary, tweak the advanced configuration for the zone, but we recommend keeping the default values unless you have specific requirements.
Click "Add Zone"
A new zone will be created and it will be populated with an NS record with the appropriate NS1 nameservers. You can also see the nameservers assigned to the zone by clicking the "Nameservers" tab atop the zone configuration page. Enter these in your registrar's portal to direct DNS traffic for the zone to NS1's nameservers.
Proceed by creating and configuring individual records in the zone.