@Dave jokers dns editing instructions are here
joker.com/faq/books/jokercom-faq-en/page/… I doubt anybody in this chat has specific experience with them. To figure out the IP address to use for the subdomain, you need to set up hosting for it, just like you did for your main site. It could be a separate account at square or hosted by a completely different company. Square may even have functionality to set up several sites under one account