how the change the shape and color of Gtk Button

["Ajax John" <ajaxjohn gmail com>]

Hi All,

I'm new to Gtk app. develoment. and trying to develop small applications.
I have 2 queries.
1)By default the shape of GtkButton is rectangle.
I want to change it's shape to some other shape, say round rectangle.
How to do that in Gtk?

2) I want to change the color of my Button to some color.
   I guess I have to create my custom style and assign it to my button...
   How to do that?

Regards,
Ajax.