How to..Afternic/ Godaddy

Maybe someone would be so kind to help me with some open questions.

Despite my research on the GoDaddy Website and the Afternic comparison table (standard/premium network) i am obviously too stupid to understand it…

I have an Afternic acount and posted 50 Domains there.
Q: How can i add the premium network?
Q: And what does it cost more than the standard network?

I dont have a GoDaddy account yet.
Q: Why should i open an account on Godaddy and why should i choose…

How to..Afternic/ Godaddy