since the kind of community is irrelevant.

First you start by buying a bunch of land, preferably around, or close to, a city.

Second you have to develop the infrastructure (water/sewer, power, etc)

Third you need an agreement with the city to provide those services to your new community

Fourth you will need to pick a name for your new community

Fifth you will need to build some parks and schools for the families in your new community

Sixth you will need to subdivide to make buyable properties

Seventh you will need to supply those subdivided properties with the services already laid down along major routs (see step #2)

Eighth you will need to start advertising the lots you just subdivided for sale

Once all the property has been bought, you now have yourself a new community.

sorry if this is not what you were looking for, your question was kinda open ended and no one really knows what community you speak of, since again, you did not say just what KIND of community you were seeking