Would you exactly identify the necessary process of foreign policy decision making? What are the steps to be taken when foreign policy is going to...

Agreed in that there is no one way in which foreign policy
decisions are made, although the Constitution clearly designates the President as being
in charge of this area of government.  In the present day, the President relies on a 
group of key Cabinet advisors to help him with foreign policy advice.  They meet,
usually daily, in a room in the White House called the Situation Room.  One type of
decision making process within that room might look something like
this:

1) The CIA Director presents the latest information
on a situation

2)  The National Security Advisor assesses
the threat to the United States in that situation

3)  The
Secretary of State gives advice about what the US decision/position should
be

4)  The Chairman of the Joint Chiefs reviews what our
military options are

5)  The Secretary of Defense advises
what our military posture in this situation should be

6) 
The President makes a decision on a course of
action

Sometimes this process happens several times a day. 
Sometimes the Vice President will be in the room to offer his perspective and so he will
be up to speed on the latest situations in case he has to take over for the
President.