Modding problem (Don't know what programs to use)

Hello. I'm not German, but this was the only site that I could maybe find help with my problem. I know this forum is pretty dead too. So the thing that I'm wondering about is what programs do I need to create custom vehicles for Cities in Motion? Thanks.

I now know which programs to use. I have Blender (With the CiM addon of course) and Gimp (With the dds plugin). I just don't know how to make models and textures.