Please help me I am so confused about how to install my Yamaha P-105 usb midi keyboard to make it usable on my Cubase AI 7 software. I don’t know what to call the software when I add it, and don’t know if there were steps I should take before that. I would be so thankful if anybody could help me because I really want to start a project and my head is BOOMING with ideas that I can’t test out because I do not have my keyboard set up. Thanks you so much ( : 
If you just want to use it as a midi controller to trigger vst instruments there is no setup to do.
Make sure it’s connected and switched on before you start Cubase.
Load Cubase and start or load a project…create an instrument track and load an instrument, hit the monitor button on the track and play.