Congrats.
You just changed the seed file which does not add any fields to Zammad.
Please use the UI or rails console (if you feel super mighty doing so).
Seeds are run during setup, so that’s not what you want.
You could use migrations, however, this is out of scope - I won’t help you further at this point, I’m sorry.
As the code you got in your seeds basically already is rails console magic, you could just run it inside the console. -However- this is not the suggested way and might thus differ from the “usual way”.
Safest way is to use the UI.
Whatever way you take, don’t forget to restart Zammad, as these changes require database updates and application reloads.