Click on the Green Wrench icon on the right hand side of the domain you wish to update the nameservers.
In the left hand column under Management click on Nameservers
Set the checkboxes to custom nameservers
By default, all 5 options will be filled in. Most people will need to delete all the options and only use the Nameservers 1 and Nameserver 2 text boxes.
If not needed, it is ok to leave Nameservers 3 through 5 blank.
