From Npp’s point of view you only provide the main menu via the function item array, everything else has to be handled by your plugin.
To do that, ask Npp for the plugin menu handle and once you have it, find the menu item you want to add sub-items to like here.
Now, to know when an npp user has clicked on such a menu item, you need to listen to the messageProc and act accordingly.
If it is necessary to manipulate the main menu of the plugin at runtime, then you need to ask Npp for a list of pre-assigned menu items.
I agree that this part could be described in more detail in the manual, which I will do soon.
If there is anything else that you think is not well described or maybe irritating, let us know.

@Alan-Kilborn

It is the same for any Windows program coding.

Creating the menu, yes, but with some Npp-related *quirks that I hope I described clearly above.

*can’t find another/better word for it.

How to create two menu layer for the Notepad++ plugins.

It is the same for any Windows program coding.
Suggest you take it to a more appropriate forum where you will get better help.
It really is off-topic here.

It’s beyond me. How to create two menu layer for the Notepad++ plugins.

I know I need to return a FuncItem * in getFuncsArray.
I see the getFuncsArray() function in PythonScript.
I think the key point is

m_funcItems[position]._init2Check = false;
m_funcItems[position]._pShKey = NULL;
m_funcItems[position]._pFunc = NULL;

Now I can use the FuncItem * array to create one menu layer, but
I still don’t know how to create two menu layer.

Please give me more information.
Thank you a lof.

John

here it is.
And here where to start.

I can not find the key point.
Do you an another example?

I will contiune to try it.
Thank you

Yes, see https://github.com/bruderstein/PythonScript for example.