Hi JTGHD,
If you genuinely want to learn and have the patience, the information is all there in the
Docs section
It also depends on what you mean by modding, whether you mean modifying the vehicle's characteristics such as
engine,
suspension or modifying the looks of a vehicle (
skins, meshes), or just installing
add-ons for vehicles.
If you're not already familiar, a good place to start is getting familiar with the
truck file format
If I may be honest, it's a lot to read, but some of it is also interesting.