That isn't really a welcome thread, so I'll answer your question here. You can download a good emulator here.
As for ROMs, it's illegal to discuss that in a thread because ROMs themselves are, technically, illegal. Do not ask that in a thread (just being safe here). I can't tell you where to go either, you'll have to search in Google. However, as a help, searching for something like "Pokemon Red ROM" or something similar is a good place to start. You'll figure out where to look. :)