First check if your pc has any midi ins/outs? If not, it should have a usb port I assume. Then buy a 5 din-5 din (standard midi) cable or usb - midi interface. You have to connect it this way - mpc's midi in to pc's midi out and then you will have mpc as slave
Of course you have to make adjustments in your machine to receive midi (midi clock or midi time code) from cubase and you have to set cubase to send midi data through computers midi out.
MY CONFUSION IS WHAT TO SELECT IN THE SYNC TAB IN CUBASE
Well,can't help you here. I'm going to launch cubase and start learning it in next couple of days, luckily, if I have the time. I suppose someone else will give you answer faster.