Depends what you mean by "join". Your FANDOM account is the same on every wiki, so effectively you've already joined all of them. Your account will have a profile page at each FANDOM site you visit. To contribute to a specific wiki, just go ahead and edit whatever you'd like to change.

Ok... but when you go to badges one says "join a wiki" and says how but idk how

To get the badge, you just need to edit a page, comment on any page (if it has comments available) or just edit your userpage. <:

Oh... ok thanks i will try it

Not sure if commenting will work now that comments are not on MediaWiki, but editing any page (including your own "About" page will definitely give you the badge. The description of the badge is just misleading.

So the badges issue is separate from what most people think as "joining". There really is no such concept, but certain things you do on a wiki will be remembered like creating a page (including a blog) , making an edit, making a Discussions or Message Wall thread, replying to one, or commenting on a page or blog. As @HumansCanWinElves said above, only wiki page creation and edits probably now count toward badges. The other stuff will put you on a list for notifications from that wiki.

Thank you all! I get it now! Thanks