How do I create a custom Normal map?

Hello, I'm trying to make a normal map to create lettering for a diesel Miramar. Does anyone know how to do this for gimp, or Paint.NET, and if I need to download anything, send me the link for the download then.

 

For Gimp, you need to download a plugin which you can find the link in the wiki with other useful tips http://wiki.beamng.com/Toolchain_overview#Gimp
Once installed, you'll need to go into the filters menu, then mapping and normal map.

Once you've created your texture, save it with you mod, and then you'll need to edit your material.cs to make it load the texture.
You'll need to put this in your material.cs : normalMap[0] = "[your normal map name and directory here]";