The way I did it was just to download OH2 again and installed it again.
When I link the Dimming pill to the In–wall switch,I can controll the light through OH.
But when I link the In-wall switch to the dimming node, nothing works.
And do I need to do the “Defining Things Using Files”(https://www.openhab.org/docs/configuration/things.html#defining-things-using-files) for this to work?
As I tried to explain before: no.
Either you need to use the autodiscovery function to generate the Things automatically (recommended) or (!) you need to define your Things via Things files.
From what I understand for your use case: you want to control your dimmer not directly through attached switches, you want to control it via a remote zwave switch?
Then you need to set up direct associations (openHAB is not involved then) or setup a rule.
Please use the search function in the forum, there are plenty of posts dealing with this.
