Blogging to please yourself. And in pleasing yourself, those who are vibrational harmony with what you write about, will be attracted to you and become your readers, your audience and your fans. This is the most natural way of forming a community.
There is no need for you to “build” a community. The community will build up itself. The community will “grow” itself. “Grow” is a better word, “build” implies too much effort.