....jogging???

i decided of jog for 30mins regularly from last week,i tried to jog at 6km speed on a threadmill ...after jogging for 10 mins(including warmup...slow walk for 5mins) i was unable to jog anymore.so i stopped n continued again after 5 mins.i was able to jog for 10 more mins.....n after dat i really felt like dieing.the next day i jogged at 5km speed and was able to jog continously for 30mins(including warm up and cooldown each for 5 mins).and this seems to be pretty comfortable for me.but does jogging at 5km...helps in reducing my weight.i'm 5"6 height and 132 pounds.....i stil want to reduce 4----5 kgs////plz help me