<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:DropDownList ID="DropDownList1" runat="server">
<asp:ListItem Text = "One" Value = "1"></asp:ListItem>
<asp:ListItem Text = "Two" Value = "2"></asp:ListItem>
</asp:DropDownList>
<asp:Button ID="Button1" runat="server" Text="Button" OnClick = "Add" />
<br />
<asp:GridView ID="GridView1" runat="server">
</asp:GridView>
protected void Add(object sender, EventArgs e)
{
DataTable dt = new DataTable();
dt.Columns.Add("TextBox");
dt.Columns.Add("DropDown");
dt.Rows.Add();
dt.Rows[0]["TextBox"] = TextBox1.Text;
dt.Rows[0]["DropDown"] = DropDownList1.SelectedItem.Text;
GridView1.DataSource = dt;
GridView1.DataBind();
}