Most of your writing revolves around creating new notes. Granted, that's a simple thing to do:
settle sync --create 'This is an interesting note'
would create a note with 'This is an interesting note' as title, within the main Zettelkasten.settle sync --create 'My second note' --project inbox
would create a note with 'My second note' as title, but in the 'inbox' project.
If you specify a project that doesn't exist yet, then it's automatically created.
However, note that this operation may fail if a note with the same title in the Zettelkasten already exists; duplicate titles are forbidden.
If you have a template file set (see: configuration), then its contents are going to be used for the newly created note. If you don't, an empty file is created. In either case, you'll have to edit the file on your own.