Where are Ghost notes??????
They are "x-ed out" notes that you finger (or position or whatever) but don't put much air behind them. ie, you imply them, but don't really play them.
You'll also set ghost notes indicated in some transcriptions (e.g. guitar solos, etc.) where - in the opinion of the transcriber - the soloist intended to play the note, but "missed." For example, there may be a fast scale run where one or more notes are inaudible, but are nonetheless implied in the structure of the run. In a case like this, if you are learning that solo, you're probably best advised not to "ghost" the notes, but rather to try to voice them normally.
In NWC, you can mimic the effect of a "ghost note" by selecting the note, CNTL-E or CNTL-Enter, tick the "Muted" check box. ;-)