How can you create something with nothing?According to Big Bang Theory.

I guess the short answer to this is that we have no idea.  We do not have any informed idea as to what existed before the moment of the Big Bang.  Any thoughts about what existed before that are more the subject of religion and faith than they are of science.

Scientists believe that, at the moment of the Big Bang, all the matter and energy that now exists was contained in just one little point.  Then that point essentially exploded and all the matter and energy came expanding out from it.

When you look at it like this, it was not a case of something coming from nothing.  There was matter and energy there before the Big Bang.  But where did the matter and energy come from?  That's the part that no one can know.