I've looked at your other threads and I have come to a conclusion that you are expecting the content creation process to be very quick. I'll give you some tips. NOTHING can be built overnight in 3D world, NOTHING can take less than 10 minutes to build. I know, I've done it and even if you work at your most efficient way, it takes weeks or it takes months to produce an object with a reasonable feature list and it takes YEARS to produce everything you want. Everything has to go through a design, development, test cycle and you need to be thorough, I am sure you would find work of mine on this forum everywhere and you can clearly see how long it takes. And I am studying at a local university, so I have piles of work to deal with as well.
To your original question:
Is there any way of reskinning trains in a simple way because I tried reskinning trains and it didn't go so well. I want plain red on the sides, and green on the nose, rear nose, and the top of the train and the fuel tank. Can you convert train files in to Trainz Paintshed?
Yes, but textures can be very confusing, it is trial and error. DO NOT use Paint Shed, its limited, and it has other problems. Also, Paint Shed gives you a false impression about textures and most locos are not supported. If you have Adobe's Photoshop (Or even The GIMP), use that, believe me, it is a lot easier as you have a lot of freedom.
If not is there any program that can set up the locomotive parts the way that Paintshed does, because in Paint Shop it has a lot of different pieces and can be confusing and when I finsih it looks really messed up.
Paintshop is a tool that is designed to a wide variety of tasks, like touching up photos, creating 3D artwork etc. So the answer to your question is yes, BUT only if you made the asset. IF someone else made it, unfortunately not and this is where you have to do some trial an error. Not everything will be in one texture file, not everything will be laid out logically either. So, you need to learn a few things. Oh, make a copy of the asset before you change anything.
In Photoshop, you need to look at Layers, the select tool and the paint bucket tool. This may help:
http://en.wikibooks.org/wiki/Trainz/Basic_Reskinning_for_beginners (Note it uses the GIMP, but the tools are pretty much similar to Photoshop, but the icons will look different).
Or this:
http://www.gaurc.us/files/info/ReskinningForDummies.pdf
The other thing, do NOT get stuck into a routine of asking "what does this tool do?", go around, experiment and play with the tools, see what it does, that is the only way you will learn. Look at other photoshop tutorials. And if you can't be bothered to do a Google search for tutorials. I'm going to put it bluntly. Good luck, you WILL NOT learn how to reskin.
(And believe me, there are a lot of tutorials out there for pretty much everything to do with photoshop, GMAX and 3D Studio Max.)
Laziness gets you nowhere.
Can I set up my reskin like Paintshop does with the simple parts? The front, the side, the top, the back, and the fuel tank?
No, not unless you do a lot of coding and that is a bigger project in itself. Each person has a different layout to their skin, so even if you do create a plugin, you need a data file that will point to the positions of each map, the size and the scaling.