how to style or theme organic groups How can i present groups on my group-list page similar to this site - 
http://www.popsugar.com/community/groups . i want there to be a picture, group title, short description of the group and total number of members.

further, how can i go about giving groups an option to have profile picture? I presume i'll have to use views but am not sure how. i am using drupal 7 and zen sub theme.
checkout this awesome og video tutorial, it will show you most of the steps needed. To add a picture to a group you just add a field type "photo" to your group node.
And to display the list of groups you'll use views. I haven't figured out yet how to show the count of members that belong to each group. I posted that as a separate question.