Insert a MIDI cable into the "MIDI OUT" jack on your Yamaha Motif keyboard. Insert the other end into a USB to MIDI audio interface. Connect the audio interface to an open USB port on your computer. Turn on the keyboard and MIDI interface.
Open the Cubase program on your computer. Select "File" and then choose "New Project." Type a name for your project and click "Save."
Click the "VST Instruments" folder in the track window. The folder sits directly beneath the "MIDI Tracks" folder. Select "Motif VST Editor" from the list of virtual instruments.
Click the "Edit" menu and then select the "Preferences" option. Click the "MIDI" tab and then check the box next to "MIDI Thru Active."
Click the "R" button on the VST track to enable it for recording. Click the red "Record" button in the upper-left corner of the window. Play the musical part you want to sequence on your keyboard. Click the "Stop" button when you want to end the recording.