Best place to make a free forum?

[Huntsong]

I want a private place for me and some friends to have discussions about an organization we're making (like Girl Scouts, but with our own stuff, we don't want to do Girl Scouts anymore, but we want to do something similar, so we were thinking about making our own thing) but it'll take a lot of planning, so I want to make a forum where we can talk about all sorts of topics, where's a free forum making site that I can trust, and use easily?