I can attach to Outlook and read the contacts from any folder with this
source:

Outlook.Application outlookApp = new Outlook.Application();
Outlook.NameSpace   outlookNamespace = outlookApp.GetNamespace("mapi");
outlookNamespace.Logon("SR", "", true, true);
Outlook.MAPIFolder cContacts = outlookNamespace.PickFolder();
foreach (Outlook.ContactItem outlookKontakt in cContacts.Items)
{
  Console.WriteLine(outlookKontakt.FullName);
}
outlookNamespace.Logoff();

But now I'd like to change fields in these contacts, or add a new contact.

Can someone point me to some hints/docs how to add new contacts via COM, or
how to change stuff in the contacts?

thanks!
Sam