The only way you'll get the keyboard & MPC to talk to each other will be to hook the MPC up to the computers MIDI port (if it has one) using regular MIDI cables, then hook the keyboard up via USB and then run a program like MIDI Yoke to allow them to communicate. All you will be able to do then is trigger each machines sounds from the other device.
If you want to record audio from the keyboard and sample it into the MPC, you will need to hook up the audio outs of the keyboard to the audio ins of the MPC.
As has been suggested by myself and others already, it's strongly advisable to read up on MIDI before attempting anything. The link I gave earlier and the link that DJ-T put up are both good places to start
Also, read the manuals of both the MPC and the keyboard too
