<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" OnRowCommand="GridView1_RowCommand" OnRowDeleting="GridView1_RowDeleting" ShowFooter="True">
            <Columns>
                <asp:TemplateField HeaderText="empid">
                    <EditItemTemplate>
                        <asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("empid") %>'></asp:TextBox>
                    </EditItemTemplate>
                    <FooterTemplate>
                        <asp:TextBox ID="footertxtid" runat="server"></asp:TextBox>
                    </FooterTemplate>
                    <ItemTemplate>
                        <asp:Label ID="Label1" runat="server" Text='<%# Bind("empid") %>'></asp:Label>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="name">
                    <EditItemTemplate>
                        <asp:TextBox ID="TextBox2" runat="server" Text='<%# Bind("empname") %>'></asp:TextBox>
                    </EditItemTemplate>
                    <FooterTemplate>
                        <asp:TextBox ID="footertxtname" runat="server"></asp:TextBox>
                    </FooterTemplate>
                    <ItemTemplate>
                        <asp:Label ID="Label2" runat="server" Text='<%# Bind("empname") %>'></asp:Label>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField ShowHeader="False">
                    <ItemTemplate>
                        <asp:LinkButton ID="LinkButton1" runat="server" CausesValidation="False" CommandName="Add"
                            Text="Add"></asp:LinkButton>
                    </ItemTemplate>
                    <FooterTemplate>
                         <asp:LinkButton ID="footerlnksave" runat="server" Text="Save" CommandName="Save"></asp:LinkButton>
                    </FooterTemplate>
                    </asp:TemplateField>
            </Columns>
        </asp:GridView>

if (e.CommandName == "Add")
        {
            GridView1.FooterRow.Visible = true;
        }
        else if(e.CommandName=="Save")
        {
            TextBox txtid = (TextBox)GridView1.FooterRow.FindControl("footertxtid");
            int id = Convert.ToInt32(txtid.Text);
            TextBox txtname = (TextBox)GridView1.FooterRow.FindControl("footertxtname");
            string name = Convert.ToString(txtname.Text);           
        }
SqlCommand cmd = new SqlCommand("insert into emp values(id,name)",con);
con.Open();
cmd.ExecuteNonQuery();
con.Close();
bindgrid();//in bindgrid write GridView1.FooterRow.Visible =false;
}