resizing widgets in scroller

I have built a scroller class to which I added a slider and label widget, howerver, I cannot get the size of the new widgets to "scale" correctly. Can someone please explain the use of QSize sizeHint(), and resizeEvent (QResizeEvent *) ? Here is my code so far....many thanks!

// create empty container for wigets
QWidget *empty_container_5 = new QWidget();

//add widgets to empty container
QtCustomLabel *label_slider_avg_1 = new QtCustomLabel(("Test1"),empty_container_5); // add label widget
label_slider_avg_1->setGeometry(0,20,100,20);

QtCustomSlider *slider_avg_1 = new QtCustomSlider(Qt::Horizontal,empty_container_5);
slider_avg_1->setGeometry(0,45,100,40);
slider_avg_1->setRange(100);
slider_avg_1->setPageSize(20); // sets page size

//add container with widgets to scroller
QtCustomScrollWidget *scroll_widget = new QtCustomScrollWidget(empty_container_5,empty_conta iner_2);
scroll_widget->setGeometry(0,50,175,100);