Which cable to use for Antenna?
It looks like you have a common RF 4 way cable splitter, with cable coming into through the green wire and 4 TVs (the other cables). You should look at the splitter closely (is this RF or digital; one in and four out?), and determine if I traced the line correctly. 

If this looks like an RF 4 way splitter, and you want to add an antenna (no more "cable TV") you just need to remove the green cable from the splitter and plug in the antenna. 

However, if you have a digital (only) splitter, it will not allow the antenna signal to pass through. If you can't be sure what kind of splitter you have, then just try it... nothing will explode if I'm wrong.



If you only have two wires from the antenna, then you need a converter like this: