You've checked the servomotor controller and the servos. You'll now connect the motor controller to the BeagleBone Black and make sure you can control the servos from it. Remove the USB cable from the PC and connect it to the BeagleBone Black. The entire system will look like this:
Let's now talk to the motor controller by downloading the Linux code from Pololu at www.pololu.com/docs/0J40/3.b. Perhaps the best way is to log in to your BeagleBone Black using PuTTY, then type
wget http://www.pololu.com/file/download/maestro-linux-100507.tar.gz?file_id=0J315. Then move the file by typing
mv maestro-linux-100507.tar.gz\?file_id\=0J315 ...