This tutorial takes you through mapping the model and applying textures.
Click on the picture to open the tutorial as a pdf file in a new window or right click to save it locally. The latest version is 1.06.
These tutorials assume you will be using the 2.49b version of Blender. I don't recommend that you use version 2.5 or up at the moment as some important features are still missing from the beta.
Blender is a 3D editing program that can be used to make models of just about anything, it is free to use and the first tutorial details where to obtain the exporters needed for Trainz.