How do I put multiple voices on the same staff?
YOu can either use layering, or if you want a chord on the same staff, then put the first note onto the staff and then for any subsequent notes in the chord, use CTRL and Enter to place the note.
There are rules about constructing chords. Read about them here :
http://www.noteworthysoftware.com/nwc2/help/MNU_ADDCHORD.htm (http://www.noteworthysoftware.com/nwc2/help/MNU_ADDCHORD.htm)