Consume PHP Web Service in asp.net

I need to consume PHP web service in asp.net. In this regard i take following steps:-

Right click on the references folder, and select Add Service Reference

Click on the advanced button

Finally click the Add Web Reference button

With the reference added, I put a button on my form, and added the following button click event handler:

private void button1_Click(object sender, EventArgs e)
{
HelloTesting htesting = new HelloTesting();
string s = htesting.hello("hello");
MessageBox.Show(s);
//string s = mc.mc_config_get_string();
}

Error is:- htesting.hello() takes 1 arguments. How do i able to resove it?