Loose wires on the UBEC will get connected to your battery (soldered or via a connector)

Servo type lead from the UBEC will connect into your receiver spare port and provide 6v to your receiver and throttle servo (regulated)

Then you will need to connect your battery (soldered or via a connector) directly to your steering servo for the unregulated supply

You will also need to run the signal wire from the receiver to the unregulated servo

A couple of servo 'y' leads will make it fairly simple

Cheers