Nodes do not really support icons next to their names. The “icon” shown on the left of the Event nodes, are not really image icons, but rather just a special font character 🙂
For example: http://www.utf8icons.com/
On the other hand, you can have image icons display on nodes if you want to, but not next to their name, but rather in place of their name (replacing the text name). To do this, you can simply add the Icon attribute above your custom node class like [Icon("MyIconName")], where “MyIconName” should be an image file found under a “Resources” named folder in the project.