How do I change the badge/lettering of a vehicle?

I'm a big novice when it comes to modding in BeamNG, and I've tried following the wiki and searching for solutions, but I'm still a bit confused.

Yes, I know you would have to use a program like Blender, but I'm still a little confused specifically on the
exact process of modifying a badge/lettering on a car in BeamNG.

Assume I wanted to modify the Gavril Vendetta so that it has a Corvette badge on the hood and Corvette lettering on the back (assuming I wouldn't post it and would only use it personally).

What are the exact files I would need to modify, how would I import the new badge/lettering, and when I import the model and the new badges/lettering I want to add, how would I go about replacing the old badges/lettering and putting the new ones on without messing anything else up? Another thing to add is that I think I have a pretty basic understanding of exporting the model as a mod into BeamNG, however I'm also confused about whether or not I would need to modify the materials file or jbeam for badges/lettering, or if I can just put the badges/lettering as a cosmetic.

 

I see, so the only files I would be editing for textures would be a .dds file, correct? And also, since Photoshop is paid, would Paint.NET be a good alternative and accomplish the same thing?