Click the "All Tabs" link

Click the Configuration Center tab

Click the Enable button under Enable Testimonials for Facebook

A new browser tab/window opens to add the Testimonials tab to your Facebook Page. Select your Facebook Page and click Add Page Tab.

Go to your Facebook Page
Click "See more" to see the Testimonials tab

Click the Testimonials tab

Enter your Salesforce.com Organization Id

Click Continue

The Testimonials tab should now load, if you've marked your testimonials as "Share Online".