Jerboa app and "subscribing" to new instances and communities

Hi everyone,

I'm new to lemmy and its app and I'm having a hard time "subscribing" to another instance or community. I'm registered on the sh.itjust.works instance and can see the main lemmy.ml in the all section but I'd like to begin curating my own list of communities. Am I doing something wrong or misunderstanding something? Any help or clarification is appreciated.