jVectorMap changing colors with my code

jVectorMap changing colors with my code

Hello All,
here below there's the code I've used to link the countries in my jVectormap.

Now I would like change the colors of the selected countries , in this case are  'it', 'fr', 'de', I'm a newbie and not too much expert, can you help me? Thanks a lot    !

<script>
    var countries = ['it', 'fr', 'de']
    $(function(){
      $('#world-map').vectorMap({
  
  onRegionOver: function(event, code){
               code = code.toLowerCase();
               if(countries.indexOf(code) == -1)
                   code = 'us';
       window.location = ' http://www.microstrategy.com/' + code;
  }
 
 });
 
    });
 </script>