Problem with rendering a page from a controller

questions
1

Hi guys. I just realized that I cannot render anything from a controller and that’s good cuz rendering belongs to other layers of MVC but look at the code
I attached below and help me please find out a way to solve my problem.

# POST /sign-up ---> creates a user
# GET /sign-up ----> shows a sign up form, controller: Web::Controllers::Registrations::New
module Web::Controllers::Registrations
  class Create
    include Web::Action

    params do
      param :user do
        param :email, type: String, presence: true
        param :password, type: String, presence: true, confirmation: true
      end
    end

    def call(params)
      if params.valid?
        # a user creation code
        #
        # HOWTO: render a page that the user was created successfuly
        # CAN_BE: redirect_to '/user-created'
      else
        # HOWTO: render "sign up" page with errors under each input element
        # like password should be at least 8 symbols long and yada and yada
      end
    end
  end
end