请问用HtmlInputFile控件通过internet从客户端上传到服务器应该如何写路径呢？

private void Button1_Click(object sender, System.EventArgs e)
{
if(upimage.PostedFile.FileName!="")
{
string fileName=upimage.PostedFile.FileName;
fileName=fileName.Substring(fileName.LastIndexOf(@"\"));
string[] s=fileName.Split('\\');
fileName=fileName.Substring(fileName.LastIndexOf(@"\"));
upimage.PostedFile.SaveAs(@"http://servername/images"+@"/"+Session["NName"].ToString()+@"/"+fileName);
}
}