GtkTextView: inserting text with different styles

[Carlos Pereira <jose carlos pereira ist utl pt>]

Hi,
Let's say I have a GtkTextView, with two color tags, red and blue:

text_view = gtk_text_view_new ();
buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (text_view));
gtk_text_buffer_create_tag (buffer, "my_red", "foreground", "#ff0000", 
NULL);
gtk_text_buffer_create_tag (buffer, "my_blue", "foreground", "#00ff00", 
NULL);

Now I want too insert "Hello World":
gtk_text_buffer_insert_at_cursor (buffer, "Hello ", -1);
gtk_text_buffer_insert_at_cursor (buffer, "World", -1);

but I want Hello to be red and World to be blue.

What is the usual procedure to achieve this?
(perhaps get the iterators for the last insertion? it should be quite
easy but apparently I could not find information about this...)

Thanks,
Carlos