At the beginning, Napoleon works with Snowball to coordinate and plan the farm events. They are usually mentioned together in a leadership role, and it is explained that the pigs are smarter than the other animals anyway. Later, however, Napoleon begins to enforce his role as a dictator instead of an equal citizen, and with the other pigs, he stops pretending to contribute. One good example of this comes after Snowball is expelled, when Napoleon authorizes the windmill project:
The plans, however, had all been prepared, down to the last detail. A special committee of pigs had been at work upon them for the past three weeks.
(Orwell, Animal Farm, msxnet.org)
This is nonsense, of course; the plans were already drawn up by Snowball, but Napoleon takes credit for them and pretends that he and the other pigs had been working hard on them all along. By taking credit for the work of others, using many more resources for himself while reducing them for others, and limiting dissent and free speech, Napoleon contributes nothing to "the common good" while allowing others to work and die for his direct benefit.
Napoleon does not contribute to society, on the contrary. He is a parasite who let's others work for him, by rules he establishes (together with Snowball), and all the animals on the farm must abide by them. The rules are formulated in such a way that they benefit to a max Napoleon and his friend, Snowball. Because the pigs pronounce the rules they create and that benefit them as unchangeable, they hereby secure a lifetime comfort. By enforcing the rules through a paramilitary police force and informants, they make sure that nobody breaks these, their, rules.
What Orwell warns against in "Animal Farm," are the dangers that come with being unaware, uninformed, and disinterested in social and political happenings around one. We all are called to be conscious and critcial citizens, and not allow politicians to run the show. In "Animal Farm," Orwell gives us an ironic and insightful account into what happens when people abandon their watchfulness and cast aside their "inalienable rights."