Share items like this:
Click "Join" on the OFA Facebook app you see across barackobama.com, authorize the app, and start sharing your activity on the site, such as videos you watched, with your friends on Facebook.
Get the word out
Once you've authorized the OFA app, you'll see a "Sharing: On" link, which lets you know that the app will automatically share some actions you take on the site to Facebook.
Control what you share
You can remove specific share actions by clicking on the "Sharing on" link, find the share action in the list that you want to remove from your Facebook Timeline, and click the red "X". Or click the “Undo” link. This will remove the story from your Timeline within 5-10 seconds.
Turning automatic sharing off is also simple—just click on the Facebook sharing toggle until you see "off"". Click the toggle again to turn sharing back on.
Remember though—the more you share, the more you help.