Insertar
------------------------------------
        protected void btngrabar_Click(object sender, EventArgs e)
        {
            try
            {
                //Con.Open();
                Conexion();
                Con.Open();
                Tab = new SqlCommand("Insert into Datos_Video values(@Rut,@Nombre,@Pelicula,@Dias,@ValD,@Total,@Desc,@TotP)", Con);
                Dadap.InsertCommand = Tab;
                Dadap.InsertCommand.Parameters.Add("@Rut", SqlDbType.Char);
                Dadap.InsertCommand.Parameters.Add("@Nombre", SqlDbType.VarChar);
                Dadap.InsertCommand.Parameters.Add("@Pelicula", SqlDbType.VarChar);
                Dadap.InsertCommand.Parameters.Add("@Dias", SqlDbType.Int);
                Dadap.InsertCommand.Parameters.Add("@ValD", SqlDbType.Int);
                Dadap.InsertCommand.Parameters.Add("@Total", SqlDbType.Int);
                Dadap.InsertCommand.Parameters.Add("@Desc", SqlDbType.Int);
                Dadap.InsertCommand.Parameters.Add("@TotP", SqlDbType.Int);
                Dadap.InsertCommand.Parameters["@Rut"].Value = txtRut.Text;
                Dadap.InsertCommand.Parameters["@Nombre"].Value = txtNom.Text;
                Dadap.InsertCommand.Parameters["@Pelicula"].Value = CboPeli.Text;
                Dadap.InsertCommand.Parameters["@Dias"].Value = txtDias.Text;
                Dadap.InsertCommand.Parameters["@ValD"].Value = txtValD.Text;
                Dadap.InsertCommand.Parameters["@Total"].Value = lblValT.Text;
                Dadap.InsertCommand.Parameters["@Desc"].Value = lblDesc.Text;
                Dadap.InsertCommand.Parameters["@TotP"].Value = lblTotP.Text;
                Dadap.InsertCommand.ExecuteNonQuery();
                Response.Write("<h3>Datos Guardados de manera exitosa</h3>");
            }
            catch (Exception RR) 
            {
                Response.Write("<p>"+RR+"</p>");
            }
        }

Actualizar
-----------------------------------
//Verificar Rut
if (txtRut.text == String.Empty)
{

}else{
try	{
	ConectarBD();
	Con.Open	
	Tabb = new SqlCommand("UPDATE ArriendVehiculos SET @NombreCli, @TipoV, @NDias, @ValorD, @ValorT, @Descuento, @Interes, @TotalP WHERE Rut = @Rut ", Conn);
	Dadap.UpdateCommand = Tabb;
     	Dadap.InsertCommand.Parameters.Add("@Rut", SqlDbType.Char);
	//Parametros
                        Dadap.UpdateCommand.Parameters.Add("@NombreCliente", SqlDbType.VarChar);
                        Dadap.UpdateCommand.Parameters.Add("@NombrePelicula", SqlDbType.VarChar);
                        Dadap.UpdateCommand.Parameters.Add("@NDias", SqlDbType.Int);
                        Dadap.UpdateCommand.Parameters.Add("@ValorDia", SqlDbType.Int);
                        Dadap.UpdateCommand.Parameters.Add("@ValorTotal", SqlDbType.Int);
                        Dadap.UpdateCommand.Parameters.Add("@Descuento", SqlDbType.Int);
                        Dadap.UpdateCommand.Parameters.Add("@TotalPagar", SqlDbType.Int);
                        Dadap.UpdateCommand.Parameters["@Rut"].Value = TxtRut.Text;
                        Dadap.UpdateCommand.Parameters["@NombreCliente"].Value = TxtNomCliente.Text;
                        Dadap.UpdateCommand.Parameters["@NombrePelicula"].Value = CboTipVeh.Text;
                        Dadap.UpdateCommand.Parameters["@NDias"].Value = Convert.ToInt32(TxtNumDias.Text);
                        Dadap.UpdateCommand.Parameters["@ValorDia"].Value = Convert.ToInt32(TxtValDia.Text);
                        Dadap.UpdateCommand.Parameters["@ValorTotal"].Value = Convert.ToInt32(LblValorTotal.Text);
                        Dadap.UpdateCommand.Parameters["@Descuento"].Value = Convert.ToInt32(CboDesc.Text);
                        Dadap.UpdateCommand.Parameters["@Interes"].Value = Convert.ToInt32(CboInt.Text);
                        Dadap.UpdateCommand.Parameters["@TotalPagar"].Value = Convert.ToInt32(TxtValDia.Text);
	Dadap.UpdateCommand.ExcecuteNonQuery();
	Con.Close();
    	}catch(RR)
	{
		Response.Write("Hoaa "+RR);
	}
}