first create xml file & add using System.Xml NAMESPACE
then create button & grid .On button click its read xml file.
STEP1.
CREATE XML FILE
<?xml version="1.0" encoding="utf-8" ?>
<ProductList>
<Products>
<ProductId>1</ProductId>
<ProductName>Rice</ProductName>
<Rate>27</Rate>
</Products>
<Products>
<ProductId>2</ProductId>
<ProductName>Wheat</ProductName>
<Rate>20</Rate>
</Products>
</ProductList>
STEP2
<asp:GridView ID="GridView1" runat="server">
</asp:GridView>
<asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />
STEP3
protected void Button1_Click(object sender, EventArgs e)
{
DataSet ds = new DataSet();
ds.ReadXml(Server.MapPath("XMLFile.xml"));
GridView1.DataSource = ds;
GridView1.DataBind();
}