Saul, actually. The rest of your idiocy isn't worth my time.
Saul was the first king of Judah.
Jeroboam was the first king of Israel. His brother Rehoboam, was king of Judah, after the death of Solomon...
http://en.wikipedia.org/wiki/Saul_the_King
You are referring to the northern of the two kingdoms that succeeded the original Kingdom of Israel after the split. The northern kingdom retained the name 'Kingdom of Israel', but its kings were obviously not the first Kings of Israel.