Chris,
I am new to trainz as well. I have just begun to repaint some rolling stock into my layout roadname: Rio Grande & Pacific. I am using Photoshop CS3. it takes some trial and error to figure out how to get the finished detail. I am using TS12 so I am not familiar to particulars of 2010, but Photoshop allows me to open and edit the TGA files, along with jpg and bmp. my advice to you is to take it slow and simple at first. You will get the hang of it as time goes on. Soon you will have fleets of your own rolling stock.
Another hint is to come up with a simple paint scheme standard for your layout. The RG&P's colors are charcoal, gold, and blue. there are some variation depending on use and practicality. but, make up a general paint scheme so you can have the colors you need as a template in some file. it will help in creating not only rollingstock, but loco as well.
I hope this helps you out.
Billy
RG&P
