This tool sends custom notifications to the device or collection that you select in the ConfigMgr Console.
By default the send notification tool will attempt to use the custom "Recast Toast" notification which includes the ability to add an icon. If it is not able to send a notification that way, it will attempt to send a notification through the Configuration Manager client. If that fails the last attempt will be to send a Windows notification.
The interface for the tool looks like the below screenshot. The advanced settings can be expanded to allow you to choose the type of notification you would like to send. The first method that is successful will be the method that the notification will be sent.
You can also select the advanced settings and choose to attempt to send the notification in a specific way.
You may select a Logo Image to send with your Recast Toast Notification. This image should be in PNG, JPG, or BMP format.