让一串字符串参数要通过 对方给你的地址 使用POST方式传递到对方那里，然后对方会返回给你XML内容，然后需要从这个XML中获取相关节点的值。
整个过程对我而言相当难。因为以前从来没用过、 有没人发个参考，或者代码示例、
自己研究吧：
http://msdn.microsoft.com/en-us/library/debx8sh9.aspx
调用web services返回XML内容
C# code:
/// <summary>
/// Get Content of one page by Post Mothod
/// </summary>
/// <param name="url">address of page</param>
/// <param name="encoding">encode or charset</param>
/// <returns>the content of page</returns>
public static string Post(string url, string accept, string contentType, string referer, string language,string postContent, CookieContainer cc, Encoding encoding, out string returnUrl) {
HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(url);
req.CookieContainer = cc;
req.Accept = accept;
req.ContentType = contentType;
req.Referer = referer;
req.UserAgent = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; SLCC1; .NET CLR 2.0.50727; InfoPath.2; .NET CLR 3.0.04506; .NET CLR 3.5.21022)";
if (!string.IsNullOrEmpty(language)) {
