try something like
<%@ Import Namespace="System.IO" %>
<asp:DataGrid id="DataGrid1" runat="server" AutoGenerateColumns="false">
 <Columns>
            <asp:BoundColumn HeaderText="File Name" 
                 DataField="Name"/>            <asp:BoundColumn HeaderText="File Size" 
                 DataField="Length"/>
         </Columns>
</asp:DataGrid>
<script language="C#" runat="server">
void Page_Load (Object o, EventArgs e)
{
  string dirName = ".";
  string realDirName = Server.MapPath(dirName);
  DirectoryInfo di = new DirectoryInfo(realDirName);
  
  DataGrid1.DataSource = di.GetFiles("*.*");
  DataGrid1.DataBind();
}
</script>