Hi, Jimmy,

it is quite simple. All you need is an USB A-B cable (I presume that your MIDI keyboard has a USB B connector plug). Plug the B end into the keyboard, and the A end into any of the three A plugs of the MIDJPRO. The module is recognizing the keyboard automatically. You do not need an external AC source, for the module is powering the keyboard through the USB connection as well.

Good luck!