Think of Activity like the Status Update feature in Facebook. It’s a quick and easy way to post items across the group, and to keep track of them.
The Activity page of the group lists all activity across the group that people have decided to share. While the initial list may appear a bit daunting, as a viewer you have the option to filter the Activity stream using the drop down menu. You can also filter the stream to only show items that mention you.
At the top of the page is where you can add a quick status update, along with a photo, video, link, or document you wish to share.