Help a newbie, how do you load the mod to work?  I download it, but I don't know how to access it

Read the readme that is usually tells where to put the folders. In your mod folder there is something called a example mod that is basically the format for a mod. Mods come with a limited number of folders with files in them. The best way is to have seperate folders for seperate mods. This doesnt work when the files have the same name. Put the files in the corresponding folder from the example mod format. 

thank you "both' for the info

The ...Galactic Civilizations 3 folder  is the root folder, where you will find all the subfolders you need for that section of the mod.

If you open the [For your games directory] folder you will find where to put the files.  Put them EXACTLY where it tells you to or it will not work properly.

Same thing with the folder marked [for your my games...] folder.

Good luck.   

Actually the star trek mod makes changes to both folders.  

the [for your games directory] modifies the original folders (mostly just add designs and changes color schemes)

the [for your my games directory] is for the documents folder.

Still have the original files I downloaded   

ok thanks everybody