How to i make a Website like a Gmod Server site

i want to make a gmod site that people can register login and chat to admins and stuff as i am making a gmod server.
i would like to know a FREE way of making a site.


sites like these:
https://forums.elysiangaming.co.uk/
http://www.civilgamers.com/
http://zarpgaming.com/

this would help thanks