You can do 2 things, or you use the default.ncf delivered with the editor and adopt it. Or create a new configuration file with a new device.

Select the device, open the properties of it and go to the tab settings: choose here for device: preamp, as brand choose Yamaha. There is only one codeset available, so you don't have to change it.

Add pages or/and open them add a button, or click on an existing button. Go to the properties tab actions and click on add IR code. A dialog will popup with a list of functions. Choose one and press ok.

You have to do this for each button.

Therefore it can be easier to take the default.ncf file and adopt the things you want.