Connect the small end of your USB cable to the USB output on your MIDI keyboard, and then connect the other end to an available USB port on your computer. USB ports are usually located in the back of the computer tower.
Power on your keyboard and your computer, and then open Cubase and wait for the software to load completely.
Go to "MIDI Device Manager" then click on the "Install Device" button.
Locate and select your MIDI keyboard from the device list located on the left.
Select the MIDI output that is connected to your device. In the case of the USB MIDI cable it will be a USB port. Close the "Device Manager" window.