I was wondering if you can hook up an fds to an nes or would you need a famicom. i think it should work but the loading door could get in the way

You would need to get an adapter that would allow you to play famicom games (which would include being able to hook up the RAM adapter) to the NES. I think I've seen someone use an adapter for a frontloading NES, but you'd be best on getting either a toploading NES or a famicom (preferrably an AV famicom so you can actually use an American TV with it). You could probably find the appropriate adapter on Ebay or Amazon.

You could with an adapter like Mars said, but if you're just looking to play SMB specifically then it would just be easier (and likely cheaper) to buy an NES cartridge for it.