Someone

 #include "Monitor.h"
 #include <QPushButton>

Monitor::Monitor(QWidget *parent)
     : QWidget(parent)
{
	 QPushButton *myButton = new QPushButton(this);
}

Monitor::~Monitor()
{
}

et le.h

#ifndef MONITOR_H
#define MONITOR_H

#include <QWidget>

class Monitor : public QWidget
{
	Q_OBJECT
	
public:
	Monitor(QWidget *parent = 0);
	~Monitor();

};

#endif 

le main

#include <QApplication>

#include "Monitor.h"

int main( int argc, char* argv[] )
{
	// create application
	QApplication a( argc, argv );

	// init application

	a.setApplicationName( "File Monitor" );
	a.setOrganizationName( "ITESOFT" );
	a.setOrganizationDomain( "www.itesoft.com" );

	Monitor myMonitor;
	myMonitor.setGeometry(100, 100, 500, 355);
	myMonitor.show();
	// start application
	return a.exec();
}