The Articles did not give a chief executive of the United States, and there was not a good system in place to elect one either. Some wanted to have the President popularly elected, but some feared that the voting pool would be uneducated.
After it was decided that the House of Representatives was going to be based off of population, there was the issue of deciding how slaves would be counted in population
The Articles said that each state would have one vote in congress, but this was ineffective since many states had much larger populations than others, but those other small states had as much influence in policy-passing as the large states
They decided that to install an electoral college which is made of electors, and is roughly proportional to the population of the states.
They agreed to count the slaves as 3/5 of a white person when counting population.
The Connecticut Compromise made two chambers of Congress: Senate and House of Representatives. The Senate would have equal representation and the House would be based off of population, taking points from both the Virginia Plan and the New Jersey Plan.