The shooting war is over in the Persian Gulf. However, the war of words about it is only now beginning. Elaine Sciolino, who has covered the Middle East during the past decade for ''The New York Times'', fires the opening salvo in an effort to explain and analyze how the war came about. She first warned us about Saddam Hussein in 1985 in an article for The New York Times Magazine . Now she tells us how Saddam came to power; why he invaded Kuwait, what effects the war's outcome will have; and what happens to the region's balance of power with Saddam's army destroyed.