1. Login to your Domain Control Panel (http://domain.indiacyberspace.com/customer) and search for the domain name.

2. Click on the Domain name in the search results to get to the Order details view.

3. Click on the Manage Child Name Server button.
 
Here, you can -

Add a Child Name Server

Enter the hostname of the Child Name Server you wish to add in the Add New Child  Name Server box, key in its IP address and proceed. A Domain Name can have any number of Child Name Servers associated with it.