Icons

A long time ago using my Montana 650t, I remember adding an airplane icon to my device.  Now, I want to do that with my new Garmin Montana 750i.  Problem is, I don't remember how I did it.  I did it to use in my "In the Air" profile.  I used that to monitor my flights as I sat by the window on flights.  It worked like a charm.  Anyone have any ideas?  Thanks in a advance.