How to declare a method as WebMethod?

To declare a method as WebMethod, write the WebMethod attribute while defining it. It is used to expose a method as Web Service method or make the method accessible from PageMethods in ASP.NET AJAX.

[WebMethod]
    public static string GetData(string f, string s)
    {
        Person p = new Person();
        p.Forename = f;
        p.Surname = s;
        // throw new Exception("Custom Error :) ");
        return SerializeObjectIntoJson(p);
    }

Thanks