下面是通过读取xml文件中的内容并显示在textbox的例子：

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml;
using System.Xml.XPath;

public partial class _Default : System.Web.UI.Page
{
    public string[] x = new string[4];
    protected void Page_Load(object sender, EventArgs e)
    {

        XmlDocument xmlDoc = new XmlDocument();
        xmlDoc.Load(Server.MapPath("table.xml"));//你的xml文件
        XmlNodeList xmlList = xmlDoc.SelectSingleNode("MapSheet").ChildNodes;
        foreach (XmlNode xmlNo in xmlList)
        {
            //XmlNodeList xe = (XmlNodeList)xmlNo;
            XmlElement xe = (XmlElement)xmlNo;
            {
                if (xe.Name == "TableName")
                {
                    y[0] = xe.InnerText;
                }

                if (xe.Name == "DataSource")
                {
                    y[1] = xe.InnerText;
                }

                if (xe.Name == "UserName")
                {
                    y[2] = xe.InnerText;
                }

                if (xe.Name == "Password")
                {
                    y[3] = xe.InnerText;
                }
            }
        }
        TextBox1.Text=y[0];
        TextBox2.Text = y[1];
        TextBox3.Text = y[2];
        TextBox4.Text = y[3];
    }

}该程序已经过测试，没有问题。
http://www.cnblogs.com/support/archive/2006/10/21/535967.html