Software is the easy part. A community is people who come back, and that is built slowly. These are the steps in the order that actually works.
1. Decide what the place is about
Narrow beats broad at the start. «Writers» is too wide to give anyone a reason to join; «people publishing serialised fiction in Spanish» is a reason. You can widen later — you cannot rescue a place nobody feels is for them.
2. Find the first ten people before the server
If ten people would not follow you there today, the server can wait. They can come from a group you already run, a mailing list, a workshop, a shop with regulars. Ten committed people make a community; a thousand curious visitors do not.
3. Get the machine
A small cloud VPS is enough to begin, and it can grow later. The platform goes on it at the Server tier — see how a community server works. If nobody around you administers servers, pay someone once to set it up properly rather than fighting it for a month.
4. Put something there first
An empty community is uninviting. Before inviting anyone, publish enough that a visitor understands what the place is: a few pages, the rules, some real content. Then hand out accounts to your first people and let them fill it.
5. Write the rules down early
What is allowed, what is not, who decides, what happens when someone breaks them. Communities rarely fail on technology; they fail when an unwritten rule is enforced for the first time and it feels arbitrary.
6. Show up
For the first months the host is the metronome: publishing, answering, welcoming. This is the part that cannot be delegated to software, and it is why most servers that stall, stall.
7. Money, last
Once there is traffic, advertising, memberships, a shop or paid tiers for your members are all yours to run — the platform takes no share. Doing this before the community exists is the most common way to lose it.
If you would rather not run it yourself
You do not have to host anything to take part: a page or a site on an existing server costs nothing while you build it yourself. The other routes in are on the Get Involved page.