Publish web service in Remote Host

I have something that has me a week ago breaking my head. I have a simple web service, more than anything else it is a test service, and I want to upload it to the server of my company "www.xxxxx.com" through FileZilla I can access the server and see the folders that the server has. If I make a web page html is a matter of pasting it in "www.xxx.com/demo" and it works correctly but if it is a web service I do the same and it does not work. They ask me that the WS be on the server so I can consume it from web pages that are created later. It must be something simple, but I'm lost. The code of the WS test is as follows, C # language developed in visual studio:

public operaciones () {

    //Elimine la marca de comentario de la línea siguiente si utiliza los componentes diseñados 
    //InitializeComponent(); 
}

[WebMethod]
public int Sumar(int x, int y)
{
    return x + y;
}

[WebMethod]
public int Restar(int x, int y)
{
    return x - y;
}

[WebMethod]
public int Multiplicar(int x, int y)
{
    return x * y;
}

[WebMethod]
public int Dividir(int x, int y)
{
    return x / y;
}

}