CCP is only used to make the config.txt file for an asset. You have to use a 3D graphic program such as Gmax or Blender to make the asset first then use CCP to make the config.txt file so it can be used in Trainz.
If you mean you want to reskin an existing billboard then you can use CM to clone an existing one then use a graphics program such as GIMP or PaintShopPro to change the texture.
Bob Weber
