group type and more

I am using the map extension geommunity what i want is for users of ES, when they make a group they have the group category to choose from. But once they choose one, i want the geommunity map to show the categories on the map so you can click thru the categories and it will only show the groups within that specific category. I spoke to creator of geomunnity and attached is his reply, but seeing how i am a newbie to ES and Joomla I want you to explain what he means. It sounds like its easy but it sounds like something i'm not use to, becuase I dont really mess with the joomla functions.