Okay backstory: I'm trying to learn how to modify the lettering on the ETK I-series, because I plan to make a version that was stolen by a foreign company and reverse engineered. I found the .dds files for the lettering and I found the .jbeam that adds them to the car but I'm stumped as to what to do or how to change that. Any help at all would be appreciated. Thanks! EDIT: Forgot to mention, the only experience I have in BeamNG modding is when I changed a few words and gave the Sunburst a normal automatic transmission. If you can help, bear in mind that I'm not too well-versed.
dds files are just an image texture. You need an image editor that's capable of opening them (ie. Photoshop with the Nvidia dds plugin) and then it's a simple matter of just editing the image to your liking and saving it. If you want to make a new separate set of lettering that doesn't overwrite the original, well that's a whole other ball game with modeling and materials. If you're making standalone mod then overwriting the original within your mod should be fine