Minecraft Xbox360 split-screen HALP?!

I have a Hitachi HDTV and the old white Xbox360 it won't let me play split screen multiplayer on it I looked it up and it said to switch the switch from tv to HDTV and when I did that the picture disappeared and someone said something about the green,Blue and red cables but Idk where to plug them in at because not things in the back to plug it into do I get the hdmi cable? If so where do I get that and where do I plug it in at I'm so confused >_

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