You will need 2 programs for repainting rolling stock. The first one is TGATOOL2. This program is used to open the ace files and send them to your paint program. And also after editing, export them (ace files) back to the model. As far as a painting program is concerned, I use my trusty old Paint Shop Pro. It has served me well for many years. But there are other programs out there that are just as good if not better. Paint.Net is one that comes to mind. Or PhotoShop. Whichever one you choose, give me or anyone else here a shout if you need help getting started.