Discourse is the best discussion forum software available. There are some other options that are a little easier to set up and integrate with you WordPress site, but Discourse beats them all when it comes to the user experience for your members. Because of that, it’s my top recommendation for building a community around your site.
You could host Discourse yourself, but you shouldn’t. Instead, you should pay for managed hosting either from discourse.org (the people who build Discourse), or DiscourseHosting.com. I recommend the latter – it’s far cheaper, and I’ve had good experiences setting that up for several clients. Follow their setup instructions and you should be good to go.
In addition to setting up your hosting account there, you’ll need to point a subdomain of your main site to their servers. For instance, our friends at KelbyOne use community.kelbyone.com for their Discourse setup. Using “community” as the subdomain is almost always my top choice.
Once you’ve got your Discourse install all set up and running, you’ll need to connect it to your WordPress site. This is the one drawback to using Discourse instead of an option that more closely integrates with WordPress – since it’s at a separate subdomain, without any tweaking your members would have to have an account in each place. Luckily, there’s a plugin that allows Single Sign-On (SSO) as well as some other goodies like auto-publishing new WP content over to the Discourse forum.
Carrying on: install that plugin, and follow the included instructions on how to sync it up with your Discourse install. Once you’ve got it all set up, you’re good to go! There’s tons you can do with Discourse and your membership site including private categories for different membership levels, using forum replies in place of comments on your WordPress site, and much more. Don’t be scared to explore!
If all of the above sounds awesome but you just don’t have the time or patience to set it up, get in touch. I actually enjoy doing this stuff and would love to help you out. Yes, my wife realizes she married a complete geek.