How to Set a Join Clan Button?

Hi,

I have since moved to Blackfyre from orizon and am loving the new theme. One of the things I have having difficulty doing is finding out how to set a “join Clan” button through the Blackfyre theme.

http://realmsunchained.com

I have created a clan but I am unsure how to allow my guild members to test it and join it on the site. How exactly do people join the clans once the site goes live?

I would prefer to solve this without providing any login details. Is there documentation?