As first step you have to register a new account in nibirumail.com and subscribe for a new application.
More information about this steps are avaible in the general guide. After created a new application you will be able to find your nibirumail_id parameter for your integration.
The nibirumail_listid identify your custom application insiede nibirumail.com.
Each nibirumail_listid covers a single domain (eg. nibirumail.com but also nibirumail.com/other-page.html).
With your nibirumail_listid parameter you are ready to build your application!