Once you see that panel slide out, click the “Edit” button at the very bottom.
Then click the plus button next to “Social” to add it to your Notification Center list.
Forever after, you can tweet, post to Facebook or LinkedIn, or send messages by opening the Notification Center panel and then clicking the icon for the service you want to use.
If you’re like me and only use a couple of those, though, you can also remove the unneeded buttons. Just hover over the “Social” section within Notification Center, click the “i” that’ll appear, and deselect anything you don’t want.
Then everything will be clean and neat!
I find this to be just swell. Sending out a quick tweet or message with only a click or two? Love. It.