How to create / make a web site forum for free?

How to create / make a web site forum for free?

free software of this site but the domain and hostingnya pay. if want to use the free cms (content management system) such as phpBB, wordpress, Drupal, and so on blogspot. if I want a forum like kaskus.us price cmsnya only about a million more. Living alone is set according to financial ability.

if I want 100% free forum try: grou.ps, freeforums.com, forumer.com, ipbfree.com, etc.
if I want 100% free blog try: WordPress.com, blogger.com, drupalsite.org, etc.

free not free from ads and general web site address is a subdomain. Beginners are advised to use only the grats. the expert may have been trying to manage hosting, domain and own cms.