Showing online users in chatroom sidebar

Hi
I am building a website ("All-In-One") with articles publishing and a chatroom. The basic is done and apparently, everything works. So, now I'm working on better styling and details. here is the repository in Github [https://github.com/bdarab/all-in-one] .
I am having a problem with the sidebar of my chatroom showing the users in the chatroom. I try many ways, "created_at", "Action Cable", "jQuery" with no avail.
I tried many tutorials online, but they were all using "Devise" or other third party gems that I have not used in my app. I have made everything from scratch, which, so far, have conflicted with my codes and break the app up.
Any suggesstions to help me through this?
Thanks.