Help with credits script

[Ludwig]

I'm new in this of scripting, so far what I did is copy the scene_Gameover from scenes and change some stuff from it (change the game over image and replace it with a credits image I made by myself and changing the music by example), later of searching a bit I found the way to create a "credtis" option in the main menu (between the continue and shutdown options), so far everything OK... but the image is a bit big for show the full image, and here is where my questions start... what can I do for make the full credits show? better than making the picture be more tiny.... what I need to do? is there a better way to do the credits show? Like in a text that move from down to above the screen (if this is the case how to do it?)... here is the script I made in the scenes part

Spoiler

#==============================================================================
# ** Scene_Credits
#------------------------------------------------------------------------------
#  This class performs Credits screen processing.
#==============================================================================


class Scene_Credits < Scene_Base
  #--------------------------------------------------------------------------
  # * Start Processing
  #--------------------------------------------------------------------------
  def start
    super
    Audio.bgm_play("Audio/BGM/Battle1", 100, 100)
    fadeout_frozen_graphics
    create_background
  end
  #--------------------------------------------------------------------------
  # * Termination Processing
  #--------------------------------------------------------------------------
  def terminate
    super
    dispose_background
  end
  #--------------------------------------------------------------------------
  # * Frame Update
  #--------------------------------------------------------------------------
  def update
    super
    goto_title if Input.trigger?C)
  end
  #--------------------------------------------------------------------------
  # * Execute Transition
  #--------------------------------------------------------------------------
  def perform_transition
    Graphics.transition(fadein_speed)
  end
  #--------------------------------------------------------------------------
  # * Play Music on Game Over Screen
  #--------------------------------------------------------------------------


  #--------------------------------------------------------------------------
  # * Fade Out Frozen Graphics
  #--------------------------------------------------------------------------
  def fadeout_frozen_graphics
    Graphics.transition(fadeout_speed)
    Graphics.freeze
  end
  #--------------------------------------------------------------------------
  # * Create Background
  #--------------------------------------------------------------------------
  def create_background
    @sprite = Sprite.new
    @sprite.bitmap = Cache.system("Credits")
  end
  #--------------------------------------------------------------------------
  # * Free Background
  #--------------------------------------------------------------------------
  def dispose_background
    @sprite.bitmap.dispose
    @sprite.dispose
  end
  #--------------------------------------------------------------------------
  # * Get Fade Out Speed
  #--------------------------------------------------------------------------
  def fadeout_speed
    return 60
  end
  #--------------------------------------------------------------------------
  # * Get Fade In Speed
  #--------------------------------------------------------------------------
  def fadein_speed
    return 120
  end
  #--------------------------------------------------------------------------
  # * Transition to Title Screen
  #--------------------------------------------------------------------------
  def goto_title
    fadeout_all
    SceneManager.goto(Scene_Title)
  end
end

Thanks in advance