Do I need all 3 cords to connect to an older model TV because I only see video in and output

If the Sat receiver has coax, use that, If you have a yellow, red and white on the TV, You can use that.
If the TV only has coax in, and Sat doesn't have a Coax out. Then you need a modulator, to convert the red, white and yellow to coax, about $5-$10 at dollar stores.