Qt PushButton Hover/Pressed icons

Qt PushButton Hover/Pressed icons

I'm beginning in Qt, and I want to set a QPushButton to a different icon
whenever somebody hovers the mouse over it. Here's my code so far:
#include <QPushButton>
QPushButton *button = new QPushButton(mainWindow);
button->setIcon(QIcon(":/icons/button.png"));
button->setIconSize(QSize(128,56);
button->setGeometry(0,0,128,56);
I've heard something about stylesheets, but I have no clue how to use them
and all the documentation is very confusing for me. Could somebody explain
how I can set the icon to ":/icons/button-hover.png" whenever the mouse
hovers on the button? Also, unless it's like exactly the same for when
it's pressed, it would be great if you could show me that too.
Thanks in advance :)