Defining a key stroke ( or strokes) to filter to notes

Here I am in the Prefernce editor. (Help also open).

I just cannot see the “New Key Command”

Sorry to be so stupid !

You’re looking at the help file for v1, but you probably have v5 of Dorico, and things are labeled differently.

Here’s the help page for v5:

Yes. It is labelled differently. This link Add Key Command - #4 by musicmaven1
then exactly solved my second problem (where do I type my key sequence.)

(FWIW, that forum post is exactly a copy/paste from the manual page I linked to above!)