Need this visual basic code converted to C#

Hello,
My credit card processor provided a VB DLL for me to use in sending data to and receiving data from them. My website is in C# so I need to figure out how to incorporate this DLL into it.

In the example from the credit card processor I am to add a reference to SendPmt.dll within the VB project and then use this code

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click

        ' Initialize string
        Dim strData As String
        Dim strReturn As String

        Dim objSendPmt As SendPmt.clsSendPmt
        objSendPmt = CreateObject("SendPmt.clsSendPmt")

        strData = Replace(txtInput.Text, vbCrLf, Chr(10))

        strReturn = objSendPmt.SendPayment(strData, "test")

    End Sub

So far in my C# attempt I have added a reference to the SendPmt.dll from the processor and a reference to Microsoft.VisualBasic.dll. I think I am on the right track using the Microsoft.VisualBasic.dll but I can't seem to get it to work.