DBAdvGlowNavigator images

I would like to use different images than the ones that appear in the DBAdvGlowNavigator.  I am adding the navigator to a advToolbar.  The images look very similar to the standard delphi images, I was expecting somehing like the menu demo had..

In any event, If i want to use my own images, what size, type (ico, png,etc) , background color would you recommend?
thank you