[openbox] Please help and be lenient to newbie

[D.T.]

On Tue, 2020-07-28 at 14:21 +0700, Budi wrote:
> $ openbox-kde-session
> /usr/local/bin/openbox-kde-session: line 20: exec: startkde: not
> found
> 

The message is clear, no?
It cannot find the "startkde" command.

Please show us:

openbox --version
which startkde
which startplasma-x11