How do I connect my xbox 360 to my samsung TV?

I have tried a couple different tv's around the hose and i can not get the picture to come in. the sound works buts for some reason when i connect my xbox to the tv the picture is fuzzy, and split in two and in black and white. the only way to get this poor picture and the audio is to use the green, red and white cords. but my xbox comes with a long grey cord that connects one end into the xbox and the other splits into two whit a red/white/yellow connectors and a set of green/blue/red connectors. I am using the one green one and the red/white from the other set. how do i get my picture to be clear and the sound to work so my kids can play xbox? HELPPPPP