You need a capture card. This is a popular one: https://www.amazon.com/dp/B00428BF1Y/

To play on your TV and capture at the same time, you need a distribution amplifier: https://www.amazon.com/dp/B010EIK6K6/

For a significant improvement in video quality, consider using S-Video instead of composite video: https://www.ebay.com/itm/132861494962

You'll also need two sets of male-to-male cables, one for the capture card and one for the TV: S-Video or composite

Also, for what it's worth, I've never heard of someone getting banned from Twitch for streaming emulators.