The electoral college is a lot like most other colleges, except instead of getting a diploma, you get to be president. First, everyone in the country gets to vote on who they want to be in the electoral college. Usually they look at their GPAs, their SAT scores, extracurricular activities, and application essays, that sort of thing.
Then once the candidates get into the electoral college, they have to take tests in all the different states. Whoever gets the highest score in a state wins that state. Some states are worth more points -- this is because the questions are harder. For example, in Wyoming, most of the questions are things like "Where's Waldo?" or "Find the six differences", so it's only worth 3 points, but in California, the questions are mostly advanced calculus and physics, so it's worth 55 points.
Candidates have to study for these tests. Usually this is done by going to a particular state and camping there to read up on the material (this is called "campaigning", which is a French word for "camping"). The parties' strengths and weaknesses usually come into play here. For example, the Democratic Party is well-known for having a big tent, which is great for bringing a lot of people with you when you campaign. But a big tent is hard to move around because it takes longer to set up and take down, so democrats tend to do better in states like New York where people are packed close together in cities -- it means they don't have to move around as much.
Once all the tests have been graded, whichever guy got more points is the winner, and he gets to graduate from the electoral college. The tests are graded on a curve, too, so even if both candidates got a lot of questions wrong, someone will always graduate.