If you already have an icon file (.ico) and just want to include it in your executable, then look at the previous post. If you want to create one, go to File >> VI Properties >> General. There, hit the Edit Icon button, and you can create your own custom icon for this VI. Once you're in the Icon Editor, you can also import in images from files. Go to Edit >> Import Picture from File. Hope this helps!
Jeremy L.
National Instruments