Hi ,
Just make
ShowFooter="True"
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
ShowFooter="True">
<Columns>
<asp:TemplateField>
<FooterTemplate>
<asp:Button ID="Button3" runat="server" Text="add" />
</FooterTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
Best regards
M.Mitwalli