Exchange ews managed api create item in public folder

I have written the following VB function to create a contact using the Exchange ews managed API.  It creates a contact in teh default contacts folder.  However I need to know how to modify it to create a contact in a public folder.  The documentation seems to be poor on this topic.  Feel free to reply if you have a solution in VB or C#.  Many thanks.

Function create_contact()
        ServicePointManager.ServerCertificateValidationCallback = New RemoteCertificateValidationCallback(AddressOf ValidateCertificate)
        Dim service As New ExchangeService(requestedServerVersion:=ExchangeVersion.Exchange2007_SP1)
        'Add a valid EWS service end point here or user Autodiscover

        service.Url = New Uri("https://server/ews/exchange.asmx")

        'Add a valid user credentials

        service.Credentials = New WebCredentials("username", "password", "domain")

        'To address the SSL challenge

        ServicePointManager.ServerCertificateValidationCallback = New RemoteCertificateValidationCallback(AddressOf ValidateCertificate)

        Try


            Dim contact As Contact = New Contact(service)

            contact.GivenName = "Brian"
            contact.MiddleName = "David"
            contact.Surname = "Johnson"
            contact.FileAsMapping = FileAsMapping.SurnameCommaGivenName
            contact.Save()



            MsgBox("Contact created!!!")

        Catch ex As Exception

            MsgBox(ex.Message)

        End Try



    End Function