Basic Name Server Question

I am very much new into linux and server management but linode documentation and community has been great in helping me learn fast.

Currently I am using Linode DNS Manager to pointing my domains to ns1.linode.com, ns2.linode.com etc. I want it to be;

ns1.mycustomdomain.com ns2.mycustomdomain.com etc and so on.

What is the easiest way to approach this ? I am not sure what keywords to search google with.

Can someone point me in the right direction ?