The following is a concise explanation of these three chapters of Rousseau's famed Social Contract Theory.
In Chapter One, Rousseau talks about the fact that man is born free but eventually concedes to what is known as Collective or General Will. Therefore, Rousseau's Social Contract Theory attaches more importance to General Will, rather than the Individual Will, even though it does highlight the fact that man is born free.
Chapter Two is a revelation into his ideology that man surrenders his free and naturally independent self, to combine to form a family. A group of families lead to the formation of a society. Therefore, the formation fo a society is attributed to the voluntary surrender of the individual will of the free man, to lead to the 'general will' of the society. He also alludes to Hobbes and Aristotle, and discusses their idea, refuting some of it while accepting the left over parts.
Chapter Three, as the title suggests, talks about the rise of the strongest in the society, as the sovereign or the leader.