All menu items for gnome desktop are stored in the following locations:
/usr/share/applications/
To create a new menu item, create a new file with the suffix .desktop directly in the directory.
vi /usr/share/applications/newitem.desktop
The contents of the file are as follows:
[Desktop Entry] Version=1.0 Name=My Program Icon=/some/path Exec=/home/danny/some/path/myprog/prog Terminal=false Type=Application StartupNotify=true Categories = Network; WebBrowser;
For a more detailed description of Desktop Entry, please see: https://developer.gnome.org/desktop-entry-spec/