title: how to set an icon on a Main window and action with QT
body: <p>Honestly I do not understand resource files and how to get so that my things can get done, because it was partially explained to me and I'm quite confused where to put icon and how to make it visible on my programs.</p>
  
  <pre><code>setWindowIcon(QIcon(":/images/icon.png")); 
  </code></pre>
  
  <p>It doesn't show up or even show a error.</p>