how to label a cairo drawings in gtk+-2.0

[Mahesh Chaudhari <mahesh chaudhari ymail com>]

Hi List,
I have drawn five circles in GtkDrawingArea as below :
 
#include <gtk/gtk.h>
#include <cairo.h>
#include<math.h>

    GtkWidget* window;
    GtkWidget* darea;
static gboolean on_expose_event(GtkWidget *widget, GdkEventExpose *event, gpointer data)
    {
        cairo_t *cr;
        cr = gdk_cairo_create(darea->window);
        cairo_arc(cr,50,60,20,0,2*M_PI);
        cairo_arc(cr,110,60,20,0,2*M_PI);
        cairo_arc(cr,170,60,20,0,2*M_PI);
        cairo_arc(cr,230,60,20,0,2*M_PI);
        cairo_arc(cr,300,60,20,0,2*M_PI);
        cairo_set_source_rgba (cr, 0.5, 0, 0, 0.5);
        cairo_fill(cr);
    }
int main(int argc, char **argv)
    {
        gtk_init(&argc, &argv);
        window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
        gtk_window_set_default_size(GTK_WINDOW(window), 400, 100);
        darea = gtk_drawing_area_new();
        gtk_container_add(GTK_CONTAINER(window), darea);
        g_signal_connect(darea, "expose-event",
          G_CALLBACK(on_expose_event), NULL);

        gtk_widget_show_all(window);
        gtk_main();
        return 0;
    }
 
I want to put label(text) above each circle, Also colour should be change after few seconds 
How can I do this ? I have to use CentOS-5.3 which has gtk+-2.10.0