Child nameservers are also known as private nameservers. You can create your own child nameservers from your domain registrar controlpanel. You need to register and set the child nameserver for your domain to point the domain to your VPS/Dedicated Server. While you register the child nameservers at your domain registrar, you will require the IP Address as well as ns1.example.com and ns2.example.com of your domain.
If you have purchased the domain from Accuwebhosting.com, please refer to Set > Private Nameserver to setup your nameserver.