ADSI IsApplicationPool.EnumAppsInPool and System.DirectoryServices

How can I use the ADSI IsApplicationPool class from C# code, what lib do I need to reference
Or can I do everything through System.DirectoryServices.

I'm trying to use the .NET System.DirectoryServices to manipulate my IIS websites.
I've been trying to disypher the ms docs but have gotten lost around the use if ADSI, IsApplicationPool.EnumAppsInPool (ADSI).
How can I use the this method/class from C# code

I want to list all websites on the IIS and maybe get their properties, I think I need to use the ADSI api, correct me if I am wrong.
msdn is missing the C# example code it promises!