I would strongly suggest, as
@Yoshioka Seijuro and
@Beerus mentioned you start out with a free solution. If you want to start with a hosted solution, that's completely free to utilize, something like Forumotion or Proboards would suit your needs. If you want to host it yourself on a .com or other tld, then you'll want a solution like SMF, MyBB, Flarum or something similar. I would not start out with XenForo, IPS or vBulletin right out of the box, as these are quite expensive and if you are unsure what you're looking to do with a forum, it wouldn't make sense to spend that sort of money on a tinkering project. Start small, build up, then upgrade to the "good stuff."