If you are talking about the shortcut editor start here: an After Effects Portal: Tutorial for KeyED Up, the shortcut editor
Personally, I've never messed with it and am not interested in modifying shortcuts I've been using for 20 years.
i was not able to download the script
but is the only way to edit some hotkey or customize hotkeys
We're in the process of migrating these scripts from the old Adobe Exchange to the new one.
For now, you can modify the keyboard shortcuts file, which is in the same folder as the other preferences files.
You can edit the keyboard shortcuts file in a text editor. The KeyEd Up script only provides a convenient interface to do so.
To access the keyboard shortcuts file, go to Preferences > General and click the Reveal Preferences In Finder/Explorer button. The file is named Adobe After Effects 13.1 Mac en_US Shortcuts.txt, or similar if using Windows or a different version. Open it in a TextEdit, Notepad, or other keyboard shortcut editor. Save the file when you're through, and restart After Effects to see the changes. Tip: on Mac OS 10.8 and later, disable the Edit > Substitutions > Smart Quotes option, otherwise you'll receive errors when After Effects starts.
How can I add new command foe Shape Layer in that text editor?
As far as I know you can't create a shortcut for creating shape layers. As far as I understand shortcuts can only be modified.
It's always seemed curious to me that there is no shortcut for creating shape layers as working with shapes is
a very common thing. Much moreso than some of things they DO have shortcuts for.
If you do not have any layer active (selected) you can just activate the shape tool and draw out your shape.
The problem with this for me is that it creates the shape layer at the top of my layer stack So I always need to move it.
Why they would include shortcuts for lights and cameras but not for shapes is just another example
the many ways in which is counter intuitive. Provide a shortcut for the layer that gets created maybe once in an entire project or composition. But no shortcut for the thing that might get created hundreds of times in a single composition.