急 winform调用WCF接口问题

写了一个登录界面，要根据WCF接口登录，我要调用ReaderService中的CheckPwd类
Reference.cs一段代码如下，我要在button__click事件中怎么编写程序？小白求过程

 public void CheckPwd([System.Xml.Serialization.XmlElementAttribute(IsNullable=true)] string identityName, [System.Xml.Serialization.XmlElementAttribute(IsNullable=true)] string identityType, [System.Xml.Serialization.XmlElementAttribute(IsNullable=true)] string userPwd, out bool CheckPwdResult, [System.Xml.Serialization.XmlIgnoreAttribute()] out bool CheckPwdResultSpecified) {
            object[] results = this.Invoke("CheckPwd", new object[] {
                        identityName,
                        identityType,
                        userPwd});
            CheckPwdResult = ((bool)(results[0]));
            CheckPwdResultSpecified = ((bool)(results[1]));
        }