1. 1.  Each State votes independently for a president.
2. 3.  Each State has a number of points (Electoral Votes) based on the size of its population.
3. 4.  Whoever wins the popular vote of that State gets the points (electoral votes).
4. 5.  Whoever gets 270 or higher points (electoral votes), wins. (270 is the majority of points )
5. 6.  The points (electoral votes) are the same number as the number of Representatives and Senators in Congress.

A national popular vote is meaningless. The reason? Imagine if 51% of the country population lived in California. A president could be elected by promising everything to that one State. The other 49 States would then have no say in choosing a president. Right now, a candidate could win the popular vote with just 11 out of 50 States. The authors of the Constitution saw this as a problem and put this measure (Electoral College) in to prevent the majority from taking advantage of the minority.

A more accurate explanation

In reality, States vote for whom they want their Electoral Representatives to vote for at the Electoral College (December 18th).

Each State nominates Electoral Representatives who will then vote the decision of the people as determined by the election.

The number of representatives is based on the population of that State. It the same way the number of Representatives are determined for the House of Representatives.

The Constitution does not require these representatives to vote the results of the election, but they are duty bound and could be prosecuted by the law if they do not. In the past, some representatives have not voted based on the election results, but has never happened in a situation that effected the results of an election.