Any tutorials for making new objects on map?

[1029lg]

Hello.
I'm designing a structure in 3D model,
and I want to import it into gta5 and see how it joins with environments.

So I want to study, to make 3D models for gta5(maybe its .ydr right), and how to make texture(.ytd?) for it.
I'm using autodesk inventor for modeling.
Please leave some links of tutorials on comment.
Thanks a lot.