at first take a textbox and add calender extender from ajax or use java script to add calender on it... and set textbox 's autopostback true and set textbox textchange event true...
like..
<asp:TextBox ID="TextBox1" runat="server" AutoPostBack="True"
ontextchanged="TextBox1_TextChanged"></asp:TextBox>
and write code for gridview here...
protected void TextBox1_TextChanged(object sender, EventArgs e)
{
}
using whare clase ....