There are two ways to get to the Control Center:

The first way is by right-clicking on the Raptr/AMD Gaming Evolved icon and then select "Control Center"


The second way is via the largest button on the Dock. (Its appearance will vary based on which app you are running.)

    



From the Control Center, you should be able to check for driver updates, enable/disable Twitch Broadcasting, as well as have access to various links to your Game Library and Preferences and other functions of the Raptr client.