>>thnx can you tell me a brief description of how i can use it for nintendo and the other stuff
That's kind of like saying, "How do I use a browser to access the internet?" Well not exactly but the point is its the way your computer talks to your iPhone when you want to manually load files on your computer. Using NES as an example, you would load the emulator with installer, and you will use SSH to load ROMs on either via Terminal or sFTP. Basically anything that isn't on installer you need SSH for.
All this stuff has been covered on the different boards many many times so just do some research.