Well, you have few ways to figure out what's the file name of any application:

1. Open the system monitor, sort processes by name then launch note application and search the list for a file named {something}-notes, etc.

2. Launch the notes application, open a terminal and issue: $ ps aux|grep note. If the notes application is named anything near note it should appear right after your cursor.

3. Perform a package search: $ yum -s note (you should have a list with all packages containing note available from your repos)

Said that, after a quick web search (ahem...) the application's filename is xfce4-notes-plugin. Now just try: $ xfce4-notes-plugin --help or $ man xfce4-notes-plugin, so on.