Tizen Developers

Hello everyone!
Tell me please, I'm not much confused as to grouplistview add new groups and elements after the application is running. I understand that I need to do, such as handling the button. But I do not understand how to add items to predefined groups or create new groups?

And tell me, in general really grouplistivew change the font or size of the text in ... I searched but did not find. I add a text element containing a addelement. Thank you!!