Open External Program - Unity 5

I already know how to run an external program within unity using
Code (CSharp):
However, what i want to do is keep fceux/fceux.exe within the games files itself, that way when I build it, everything comes with the game (in this case, my application).

From what I read online, i would need to keep fceux/fceux.exe in the same directory as the launcher, however with Unity 5 I can’t seem to find where that’s at in my project folder. Where do I need to put the folder?

Put the file in a folder called StreamingAssets. The file will then be included in the data files that come along with the launcher. The path of the executable at runtime can be determined like so:

string filePath = System.IO.Path.Combine(Application.streamingAssetsPath, "fceux.exe");