BuddyPress.org

Please read the instructions provided in the previous post.

All you need to do is create a new folder in /wp-content/themes/.
Then you create a stylesheet with the data listed in the tutorial.

Next, you should copy over “/wp-content/plugins/buddypress/bp-themes/bp-default/groups/groups-loop.php” to your new theme, maintaining the directory structure.

eg. /wp-content/themes/YOUR_NEW_THEME/groups/groups-loop.php

Then make your changes there.