Questions about emulaters

[Two Socks]

Hi everyone:
I recently learned through a friend that it is possible to download and play old Nintendo games on my pc. I thought I'd be in Heaven once I got everything set up, but instead, I have nothing but problems. The emulater I installed is JNES 0.5.2. I can't seem to get a controller to work with it, and I need the game play area of the screen to fill the entire screen. Even when fully maximumized, the play area is still only in the center of the screen. I am great with knowing computers and how they work, but I know nothing about these emulaters or different types of pc controllers, so I really need help here in choosing an emulater that works for me. If this is not the right place to ask for help, please point me to where I need to go.
Thanks,
Two Socks