LoginInfo loginInfo = new LoginInfo();
xmlNode = _xml.SelectSingleNode(loginUrl);
loginInfo.LoginUrl = xmlNode.InnerText;
xmlNode = _xml.SelectSingleNode(loginUser);
loginInfo.UserId = xmlNode.Attributes["tagId"].Value;
loginInfo.UserValue = xmlNode.InnerText;
xmlNode = _xml.SelectSingleNode(loginPwd);
loginInfo.PwdId = xmlNode.Attributes["tagId"].Value;
loginInfo.PwdValue = xmlNode.InnerText;
xmlNode = _xml.SelectSingleNode(loginBtnId);
loginInfo.BtnId = xmlNode.InnerText;   

 <login>
      <url>//www.49028c.com/JLxxxxn/Lxxxxx.aspx</url>
      <user tagId="txtAccount">xxxx</user>
      <pwd tagId="txtPassword">xxxxx</pwd>
      <btnId>btnLogin</btnId>
    </login>