get namespace rest api

I was following this section.

https://msdn.microsoft.com/en-us/library/azure/dn140232.aspx

I can create namespace and delete namespcae,but I can't get namespace.

It returned 403 Forbidden.

I don't know what the authentication it needs. and what the contents of header need to put.

I do it like create method, but it return 400 bad request.

How can I do?

Thank you.