What exactly do you mean by "can't get it"? It doesn't run? Throws an error?

Oh, sorry. Well first, it's not a mod so you shouldn't extract it there. It's a separate program .exe that you can run from anywhere. The download pack has a bunch of folders when you extract the .rar, there should be a Galaxy Forge folder with the .exe in there.

Note that you do need the .NET Framework 2.0 to run it. You can check your version by going to add/remove programs and it will show up. If you don't have it listed there, you'll need to grab the distributable off Microsoft's site. 2.0 is pretty old, think the latest is 3.5 and it works fine.

But yeah, Galaxy Forge won't show up anywhere in game, since it's separate

Nope, that's got nothing to do with it. What issues are you having with downloading mods?

Double check the folder structure, it's very important. It should look something like this (excuse the crappy formatting )

\Mods\

    \ModName\

           \GameInfo

           \String

           ...

The "ModName" folder is what the game looks for when it's displaying mods in Options > Mods, and inside it needs to have all the appropriate folders, depending on what the mod needs. GameInfo, String, Window, Textures, Particle, whatever - depends on the mod.

Well all mods come in an archive (rar, zip, etc). Did you extract it? (sorry, I know it's a dumb question, but I need to be clear )

Your path is correct, and if you extracted there but don't have the folders, check your archiver app and make sure that it's set to extract Folders & Path names. Unless whoever made the mod did a sloppy job packaging it, it should already be set up in appropriate folders and paths and all you should have to do is extract it into \Mods

What are you using to extract the mod?

That command just zips it again - (you should notice that the "folder" icon at your destination has a zipper).

Instead double click on the archive to open it in whatever program (or windows) and choose to "extract" the contents to your target location.