How to add commands to a cascaded menu?

[Rick Macdonald]

When I use Compound/Insert/System/MenuBar, and edit the Open
to be a cascade rather than a command, I can't figure out how to add
commands to the cascaded menu. I did discover that you have to click
"Update" to make the "cascade" _stick_, otherwise it keeps changing back
to "command".

What's the trick for adding commands to the cascaded menu?

...RickM...