On the back of the display, facing downwards, you will find these ports. Be careful not to use the DisplayPort Out by mistake.
To connect two Macs at 2560×1080 resolution you will need an additional Mini Display Port to Mini DisplayPort cable, like the white one shown here.
The cables connected, with USB 3.0 (uplink) cable shown on the right.
The display has 2 USB ports next to the uplink port behind the display and 2 more on the side which frees up the 2nd USB port on the MacBook Pro.