1997 Mazda 626 There Crack Exhaust Manifold Lot Oil Comming Out While Driving

There is a crack in my exhaust manifold, and lot of oil is comming out from there while driving, which makes the car to bring out blue smoke. Where is the oil gaining entrance from? Because one of the plug is soaked with oil, and there is engine oil in that cylinder where the spark plug was. Please tell me the particular place oil can pass to the cylinder and then to the exhaust?