announcement-test/app/controllers/admin/announcements_controller.rb

class Admin::AnnouncementsController < ApplicationController
  def new
  	@announcement = Bulletin.new
  end

  def create
  	@announcement = Bulletin.new(bulletin_params)
  	@announcement.save
  end

  def index
    @announcements = Bulletin.all
  end

  private

    # Never trust parameters from the scary internet, only allow the white list through.
    def bulletin_params
      params.require(:bulletin).permit(title_translations: [:en, :zh_tw], body_translations: [:en, :zh_tw])
    end
end