connect a qpushbutton a slot

[Lycus HackerEmo]

I am creating a text editor. I create 2 QPushButton one called Abrir and a Guardar, as you do for that clicking these button do what it say the slot?

void on_menuGuardar_triggered();
void on_menuAbrir_triggered();

and another question. in most of the programs in the Help menu, is an option called About. the windows is a QDialog or QMessageBox?