how did the domestication of agriculture contributed to the development of the first civilizations?

Answer 1

The advent of agriculture allowed populations to produce surplus sustinence (food) and was able to support larger populations. Likewise, manipulation of some kind of irrigation was necessary, creating a demand for control of natural resources like water and land, which created conflict, and with a growing population comes more social complexity and the emergence of different "social classes" as societies became more and more complex, it was necessary for some administrative force to take control and eventually you see the emergence of early states, or civilizations (although that word is falling out of use in anthropological studies). That's it in a nutshell, you might want to try to check out articles on the subject of the transition to complexity on JSTOR if you have access, Lewis Binford is a good place to start.

Answer 2

The short answer is it let people stay in one place making the accumulation of goods possible, and since food was more available, it allowed people to specialize, such as making spearpoints, or basket weaving or whatever leading to better quality.

Answer 3

It allowed people to grow their own food. This meant that there was more food available.
Everyone didn't have to move their herds around seasonally or go hunting so often.

Because there was more food, people could settle down and make permanent communities.
People could keep more possessions, too, since they didn't have to carry everything around with them.

Answer 4

Nomadic peoples started to settle down, and where one was, others followed.