Article 1 - Legislative
The Constitution is logically divided into 7 articles. It's a remarkably short document. I was able to create all these MP3 files in a morning.
Article 1 (I'll use the Latin numerals even though the Constitution uses Roman numerals. We're more accustomed to Latin numerals) discusses the House of Representatives and the Senate - the two branches of our legislature, which is responsible for making our laws. The House is representated by population. The larger the state, the more representatives. The Senate is represented by state. Each state, no matter how large, has two Senators. The idea is to balance the interests of the states with large population (who could be expected to dominate in the House) with the interests of the states with small population (who could have a more equal playing field in the Senate).
Whether the Founding Fathers achieved that balancing goal is an interesting question. Compounding the question is that slaves were considered, for the purpose of representation in the House, as 3/5 of a person - even though they didn't vote! This created a huge advantage for the Southern states, and in fact was an incentive for Southerners to add to their slave property. The South, up to the Civil War, dominated the national government - including the Presidency - because of this. Evil was thus rewarded.