The website you are viewving lies in the so-called "deep web", requiring the use of the Tor browser to access it. There is nothing overtly interesting about it - most of it is as exactly as you would expect, links to a manifesto calling for humanity to unite against mutants, links to backup copies of news articles both old and new, and quotes from certainly human important figures from history.
Two features do stand out, however. One is a small legend which says: "Remember the circled fist, the symbol of our Brotherhood." The second one is a "guestbook" feature reminiscent of the early days of the Internet, except only the option to send a written message is seen - what the visitors of the website has written is evidently kept private.
Should you have any business with the Brotherhood of Humanity, this is likely a good route as any to contact them.
