Smr Simple!

How does one take a map that you download from this board and then modify it?

New to maps, so excuse me if this is a beginner's question.

First you ought to get to know the structure of the maps. I suggest you read the mapmaking tutorial and make up your mind what kind of a modification you want to do.
http://www.smrsimple.com/forums/viewtop ... =42&t=4226

There are literally hundreds of posts written on this subject.
Study the how the Terrain Editor works, that will give you an idea what kind of a modifications can be had.
Jancsika

I know some of the changes I would like to make, but my problem is more fundamental. I can't find a file anywhere in the downloaded directories that accompany the file that the terrain editor will open. How does one open those maps?

You can’t find those files, because the mapmakers normally don’t send it along with the maps. That would allow people to mess up their map and claim that there is something wrong with it.
If you want to you can get into my PITGOC map. After you have downloaded it and installed it, start a new game and open the “Terrain Editor”
There click on: “Load a Saved Map”
Then click on PITGOC.SMR_Scenario
Click OK.
Now you can edit the map part. Cities,resources, terrain etc
To edit the trains you have to edit the RRT_Trains_PITGOC.XML file with a good XML editor. (Notepad++ with the XML plugin, is free)
Jancsika

"That would allow people to mess up their map and claim that there is something wrong with it."

Thats not why. Map makers just don't think about it.

More fundamentally maps were first made without the map maker and as such the community got into the habit of not including extra files.