Hullo you asked for help so here goes,

Behind the smile of a lovely day
a new beginning ahead
startS IN a simple way
walking IN the crowd
with so many thoughts unknown
dreaming and thinking
what should be the 1st THING to do.

everyday of our life
many A journey WILL PASS US by
each path has their own consequences

many miles before WE reach the goal
some miles you took
could be the best for you
and somehow it could be the opposite
it might BE THE worst nightmare ever

behind the smile, is full of THE challenges in life
and every road we take
could be a short or long journey
but only you make your own life and destiny

Well thats the best i could do in the short time i had , look carefully and you will see commas have been added and some changes i highlighted in capitals
Your poem was very good and i enjoyed reading it good job well done