Going by your previous post are you are still using GTK+ 2.24?
You will need to create your tool bar as normal see documentation at
http://developer.gnome.org/gtk/stable/GtkToolbar.htmlYou will then need to create your individual buttons by creating a GtkToolButton, see documentation at
http://developer.gnome.org/gtk/stable/GtkToolButton.html that way you can set the label and icon.
Code:
...
GtkWidget *toolbar = gtk_toolbar_new();
GtkWidget *tb1 = gtk_tool_button_new(GTK_WIDGET(icon), "Text");
gtk_toolbar_insert(GTK_TOOLBAR(toolbar), tb1, 0);
...